Service manual

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Table Of Contents

TABLE OF CONTENTS

5D7-F8197-E0

YAMAHAR125.COM

SERVICE MANUAL

YZF-R125

Summary of content (356 pages)

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YAMAHAR125.
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YamahaR125.COM For more information about Yamaha R125 Login to http://www.yamahar125.com EAS20060 YZF-R125 SERVICE MANUAL © by MBK Industrie First edition, January 2008 All rights reserved. Any reproduction or unauthorized use without the written permission of MBK Industrie is expressly prohibited.
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YamahaR125.COM EAS20070 NOTICE This manual was produced by MBK Industrie. primarily for use by Yamaha dealers and their qualified mechanics. It is not possible to include all the knowledge of a mechanic in one manual. Therefore, anyone who uses this book to perform maintenance and repairs on Yamaha vehicles should have a basic understanding of mechanics and the techniques to repair these types of vehicles.
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YamahaR125.COM EAS20090 HOW TO USE THIS MANUAL This manual is intended as a handy, easy-to-read reference book for the mechanic. Comprehensive explanations of all installation, removal, disassembly, assembly, repair and check procedures are laid out with the individual steps in sequential order. • The manual is divided into chapters and each chapter is divided into sections. The current section title “1” is shown at the top of each page.
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YamahaR125.COM EAS20100 SYMBOLS The following symbols are used in this manual for easier understanding. NOTE: The following symbols are not relevant to every vehicle. 2 3 4 5 6 7 8 T. 1 R. 9 10 E 11 G 12 M 13 BF 14 B 15 LS 16 M 17 S 18 LT New 1. Serviceable with engine mounted 2. Filling fluid 3. Lubricant 4. Special tool 5. Tightening torque 6. Wear limit, clearance 7. Engine speed 8. Electrical data 9. Engine oil 10. Gear oil 11. Molybdenum disulfide oil 12. Brake fluid 13.
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YamahaR125.
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YamahaR125.
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YamahaR125.
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YamahaR125.COM GENERAL INFORMATION IDENTIFICATION ............................................................................................ 1-1 VEHICLE IDENTIFICATION NUMBER ..................................................... 1-1 MODEL LABEL.......................................................................................... 1-1 FEATURES...................................................................................................... 1-2 OUTLINE OF THE FI SYSTEM................................
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YamahaR125.COM EAS20130 IDENTIFICATION EAS20140 VEHICLE IDENTIFICATION NUMBER The vehicle identification number “1” is stamped into the right side of the steering head pipe. 1 EAS20150 MODEL LABEL The model label “1” is affixed to the frame. This information will be needed to order spare parts.
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FEATURES YamahaR125.COM EAS20170 FEATURES EAS5D71022 OUTLINE OF THE FI SYSTEM The main function of a fuel supply system is to provide fuel to the combustion chamber at the optimum air-fuel ratio in accordance with the engine operating conditions and the atmospheric temperature.
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FEATURES YamahaR125.COM EAS5D71023 FI SYSTEM The fuel pump delivers fuel to the fuel injector via the fuel filter. The pressure regulator maintains the fuel pressure that is applied to the fuel injector at only 250 kPa (2.50 kg/cm², 36.3 psi). Accordingly, when the energizing signal from the ECU energizes the fuel injector, the fuel passage opens, causing the fuel to be injected into the intake manifold only during the time the passage remains open.
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FEATURES YamahaR125.COM To reset a tripmeter, select it by pushing the “RESET/SELECT” button briefly (less than one second), and then push the button for at least three seconds while the selected tripmeter is flashing. If you do not reset the fuel reserve tripmeter manually, it will reset itself automatically and the display will return to the prior mode after refueling and traveling 5 km (3 mi). EAS5D71046 MULTI-FUNCTION DISPLAY 1 Fuel meter 2 1. Multi-function display 2.
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IMPORTANT INFORMATION YamahaR125.COM EAS20180 IMPORTANT INFORMATION EAS20190 PREPARATION FOR REMOVAL AND DISASSEMBLY 1. Before removal and disassembly, remove all dirt, mud, dust and foreign material. EAS20210 GASKETS, OIL SEALS AND O-RINGS 1. When overhauling the engine, replace all gaskets, seals and O-rings. All gasket surfaces, oil seal lips and O-rings must be cleaned. 2. During reassembly, properly oil all mating parts and bearings and lubricate the oil seal lips with grease. 2.
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YamahaR125.COM EAS20230 BEARINGS AND OIL SEALS Install bearings “1” and oil seals “2” so that the manufacturer’s marks or numbers are visible. When installing oil seals “1”, lubricate the oil seal lips with a light coat of lithium-soap-based grease. Oil bearings liberally when installing, if appropriate. ECA13300 CAUTION: Do not spin the bearing with compressed air because this will damage the bearing surfaces.
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YamahaR125.COM CHECKING THE CONNECTIONS EAS20250 CHECKING THE CONNECTIONS Pocket tester 90890-03112 Analog pocket tester YU-03112-C Check the leads, couplers, and connectors for stains, rust, moisture, etc. 1. Disconnect: • Lead • Coupler • Connector 2. Check: • Lead • Coupler • Connector Moisture → Dry with an air blower. Rust/stains → Connect and disconnect several times. NOTE: • If there is no continuity, clean the terminals. • When checking the wire harness, perform steps (1) to (3).
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SPECIAL TOOLS YamahaR125.COM EAS20260 SPECIAL TOOLS The following special tools are necessary for complete and accurate tune-up and assembly. Use only the appropriate special tools as this will help prevent damage caused by the use of inappropriate tools or improvised techniques. Special tools, part numbers or both may differ depending on the country. When placing an order, refer to the list provided below to avoid any mistakes. NOTE: • For U.S.A.
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SPECIAL TOOLS YamahaR125.COM Tool name/Tool No. Illustration Reference pages Steering nut wrench 90890-01403 Spanner wrench YU-33975 3-22, 4-54 Damper rod holder 90890-01294 Damping rod holder set YM-01300 4-48, 4-49 YM-01300 T-handle 90890-01326 T-handle 3/8" drive 60 cm long YM-01326 4-48, 4-49 Fork seal driver weight 90890-01367 Replacement hammer YM-A9409-7 4-49, 4-50 YM-A9409-7/YM-A5142-4 Fork seal driver attachment (ø33) 90890-01368 Replacement 33 mm YM-A9409-4 4-49 Yamaha bond No.
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SPECIAL TOOLS YamahaR125.COM Tool name/Tool No. Illustration Reference pages Valve spring compressor 90890-04019 YM-04019 5-18, 5-23 Valve spring compressor attachment 90890-04108 Valve spring compressor adapter 22 mm YM-04108 5-18, 5-23 Valve guide remover (ø4.5) 90890-04116 Valve guide remover (4.5 mm) YM-04116 5-19 Valve guide installer (ø4.5) 90890-04117 Valve guide installer (4.5 mm) YM-04117 5-19 Valve guide reamer (ø4.5) 90890-04118 Valve guide reamer (4.
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SPECIAL TOOLS YamahaR125.COM Tool name/Tool No.
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SPECIAL TOOLS YamahaR125.COM Tool name/Tool No.
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SPECIAL TOOLS YamahaR125.COM Tool name/Tool No.
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YamahaR125.COM SPECIFICATIONS GENERAL SPECIFICATIONS ........................................................................ 2-1 ENGINE SPECIFICATIONS ............................................................................ 2-2 CHASSIS SPECIFICATIONS .......................................................................... 2-9 ELECTRICAL SPECIFICATIONS ................................................................. 2-12 TIGHTENING TORQUES .............................................................
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YamahaR125.COM GENERAL SPECIFICATIONS EAS20280 GENERAL SPECIFICATIONS Model Model 5D71 (Europe) Dimensions Overall length Overall width Overall height Seat height Wheelbase Ground clearance Minimum turning radius 2015 mm (79.3 in) 660 mm (26.0 in) 1065 mm (41.9 in) 818 mm (32.2 in) 1355 mm (53.3 in) 155 mm (6.10 in) 3100 mm (122.0 in) Weight With oil and fuel Maximum load 138.
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ENGINE SPECIFICATIONS YamahaR125.COM EAS20290 ENGINE SPECIFICATIONS Engine Engine type Displacement Cylinder arrangement Bore × stroke Compression ratio Standard compression pressure (at sea level) Liquid cooled 4-stroke, SOHC 124.7 cm³ Forward-inclined single cylinder 52.0 × 58.6 mm (2.05 × 2.31 in) 11.20 :1 550 kPa/600 r/min (78.2 psi/600 r/min) (5.5 kgf/cm²/600 r/min) 480–620 kPa (68.3–88.2 psi) (4.8–6.
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YamahaR125.COM Thermostat Model/manufacturer Valve opening temperature Valve full open temperature Valve lift (full open) Radiator core Width Height Depth Water pump Water pump type Reduction ratio ENGINE SPECIFICATIONS 5YP/NIPPON THERMOSTAT 80.5–83.5 °C (176.9–182.3 °F) 95.0 °C (203.0 °F) 3.0 mm (0.12 in) 198.0 mm (7.80 in) 128.0 mm (5.04 in) 24.0 mm (0.94 in) Single suction centrifugal pump 19/38 (0.500) Spark plug (s) Manufacturer/model Spark plug gap NGK/CR8E 0.7–0.8 mm (0.028–0.
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YamahaR125.COM ENGINE SPECIFICATIONS Timing chain Model/number of links Tensioning system DID SCR-0404SV/96 Automatic Rocker arm/rocker arm shaft Rocker arm inside diameter Limit Rocker arm shaft outside diameter Limit Rocker-arm-to-rocker-arm-shaft clearance Limit 9.985–10.000 mm (0.3931–0.3937 in) 10.015 mm (0.3943 in) 9.966–9.976 mm (0.3924–0.3928 in) 9.941 mm (0.3914 in) 0.009–0.034 mm (0.0004–0.0013 in) 0.074 mm (0.
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YamahaR125.COM ENGINE SPECIFICATIONS Limit Valve-stem-to-valve-guide clearance (intake) Limit Valve-stem-to-valve-guide clearance (exhaust) Limit Valve stem runout 4.550 mm (0.1791 in) 0.010–0.037 mm (0.0004–0.0015 in) 0.080 mm (0.0032 in) 0.025–0.052 mm (0.0010–0.0020 in) 0.100 mm (0.0039 in) 0.010 mm (0.0004 in) Cylinder head valve seat width (intake) Limit Cylinder head valve seat width (exhaust) Limit 0.90–1.10 mm (0.0354–0.0433 in) 1.6 mm (0.06 in) 0.90–1.10 mm (0.0354–0.0433 in) 1.6 mm (0.
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YamahaR125.COM Height H ENGINE SPECIFICATIONS 5.0 mm (0.20 in) H D Offset Offset direction Piston pin bore inside diameter Limit Piston pin outside diameter Limit Piston-pin-to-piston-pin-bore clearance Limit 0.50 mm (0.0197 in) Intake side 14.002–14.013 mm (0.5513–0.5517 in) 14.043 mm (0.5529 in) 13.995–14.000 mm (0.5510–0.5512 in) 13.975 mm (0.5502 in) 0.002–0.018 mm (0.0001–0.0007 in) 0.068 mm (0.0027 in) Piston ring Top ring Ring type Dimensions (B × T) Barrel 0.80 × 1.90 mm (0.03 × 0.
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ENGINE SPECIFICATIONS YamahaR125.COM Runout limit C Big end side clearance D Big end radial clearance E C 0.030 mm (0.0012 in) 0.110–0.410 mm (0.0043–0.0161 in) 0.004–0.014 mm (0.0002–0.
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YamahaR125.COM ENGINE SPECIFICATIONS Shifting mechanism Shift mechanism type Shift fork thickness Shift fork thickness Shift drum and guide bar 5.76–5.89 mm (0.227–0.232 in) × 1 4.76–4.89 mm (0.187–0.193 in) × 2 Decompression device Device type Auto decomp Air filter Air filter element Dry element Fuel pump Pump type Model/manufacturer Output pressure Electrical 5B2/BITRON 250.0 kPa (36.3 psi) (2.
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YamahaR125.COM CHASSIS SPECIFICATIONS EAS20300 CHASSIS SPECIFICATIONS Chassis Frame type Caster angle Trail Semi double cradle 24.20 ° 86.1 mm (3.39 in) Front wheel Wheel type Rim size Rim material Wheel travel Radial wheel runout limit Lateral wheel runout limit Wheel axle bending limit Cast wheel 17xMT2.75 Aluminum 130.0 mm (5.12 in) 0.5 mm (0.02 in) 1.0 mm (0.04 in) 0.25 mm (0.
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YamahaR125.COM Front disc brake Disc outside diameter × thickness Brake disc thickness limit Brake disc deflection limit Brake pad lining thickness (inner) Limit Brake pad lining thickness (outer) Limit Master cylinder inside diameter Caliper cylinder inside diameter Recommended fluid CHASSIS SPECIFICATIONS 292.0 × 4.0 mm (11.50 × 0.16 in) 3.5 mm (0.14 in) 0.15 mm (0.0059 in) 4.5 mm (0.18 in) 0.8 mm (0.03 in) 4.5 mm (0.18 in) 0.8 mm (0.03 in) 11.00 mm (0.43 in) 28.00 mm × 2 (1.
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YamahaR125.COM CHASSIS SPECIFICATIONS Rear suspension Type Spring/shock absorber type Rear shock absorber assembly travel Spring free length Installed length Spring rate K1 Spring stroke K1 Optional spring available Swingarm (monocross) Coil spring/oil damper 54.0 mm (2.13 in) 162.0 mm (6.38 in) 155.0 mm (6.10 in) 103.00 N/mm (588.13 lb/in) (10.50 kgf/mm) 0.0–54.0 mm (0.00–2.
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YamahaR125.COM ELECTRICAL SPECIFICATIONS EAS20310 ELECTRICAL SPECIFICATIONS Voltage System voltage 12 V Ignition system Ignition system Advancer type Ignition timing (B.T.D.C.) TCI (digital) Throttle position sensor and electrical 5.0°/1400 r/min Engine control unit Model/manufacturer 5D700/YAMAHA Ignition coil Model/manufacturer Minimum ignition spark gap Primary coil resistance Secondary coil resistance 2JN/YAMAHA 6.0 mm (0.24 in) 2.16–2.64 Ω at 20 °C (68 °F) 8.64–12.
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YamahaR125.COM ELECTRICAL SPECIFICATIONS Indicator light Neutral indicator light Turn signal indicator light High beam indicator light Coolant temperature warning light Engine trouble warning light LED LED LED LED LED Electric starting system System type Constant mesh Starter motor Model/manufacturer Power output Armature coil resistance Brush overall length Limit Brush spring force Commutator diameter Limit Mica undercut (depth) 3C1/YAMAHA 0.20 kW 0.0315–0.0385 Ω 7.0 mm (0.28 in) 3.50 mm (0.
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YamahaR125.COM ELECTRICAL SPECIFICATIONS Radiator fan Model/manufacturer Running rpm SSW6101/PANASONIC 4800 r/min Fan motor relay Model/manufacturer ACM33211 M05/MATSUSHITA Fuses Main fuse Headlight fuse Signaling system fuse Ignition fuse Radiator fan fuse Spare fuse Spare fuse Spare fuse Spare fuse 20.0 A 15.0 A 7.5 A 7.5 A 5.0 A 20.0 A 15.0 A 7.5 A 7.
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YamahaR125.COM EAS20320 TIGHTENING TORQUES EAS20330 GENERAL TIGHTENING TORQUE SPECIFICATIONS This chart specifies tightening torques for standard fasteners with a standard ISO thread pitch. Tightening torque specifications for special components or assemblies are provided for each chapter of this manual. To avoid warpage, tighten multi-fastener assemblies in a crisscross pattern and progressive stages until the specified tightening torque is reached.
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YamahaR125.COM TIGHTENING TORQUES EAS20340 ENGINE TIGHTENING TORQUES Item Thread Q’ty size Tightening torque Remarks Cylinder head bolt M8 4 22 Nm (2.2 m·kg, 16 ft·lb) E Cylinder head bolt M6 2 10 Nm (1.0 m·kg, 7.2 ft·lb) E Spark plug M10 1 13 Nm (1.3 m·kg, 9.4 ft·lb) Cylinder head cover bolt M6 5 10 Nm (1.0 m·kg, 7.2 ft·lb) Oil check bolt M6 1 7 Nm (0.7 m·kg, 5.1 ft·lb) Exhaust pipe stud bolt M8 2 15 Nm (1.5 m·kg, 11 ft·lb) Coolant drain bolt M6 1 7 Nm (0.7 m·kg, 5.
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YamahaR125.COM Item Thread Q’ty size TIGHTENING TORQUES Tightening torque Remarks Air induction system reed valve bolt M6 2 10 Nm (1.0 m·kg, 7.2 ft·lb) Exhaust pipe nut M8 2 20 Nm (2.0 m·kg, 14 ft·lb) Exhaust assembly bolt M8 1 20 Nm (2.0 m·kg, 14 ft·lb) Exhaust assembly bolt M8 1 20 Nm (2.0 m·kg, 14 ft·lb) Crankcase bolt M6 2 10 Nm (1.0 m·kg, 7.2 ft·lb) Crankcase bolt M6 6 10 Nm (1.0 m·kg, 7.2 ft·lb) Crankcase bolt M6 4 10 Nm (1.0 m·kg, 7.
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TIGHTENING TORQUES YamahaR125.COM Cylinder head tightening sequence: 1 3 5 6 4 2 Generator cover tightening sequence: 1,6 7 8 5 4 9 3,11 2,10 Clutch cover tightening sequence: 6 1,7 9 8 9 5 4 10 2,12 11 3,13 Crankcase tightening sequence: B A 14 7 1,6 8 5 9 2,12 4 3,13 15 11 10 A. Left crankcase B.
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YamahaR125.COM TIGHTENING TORQUES EAS20350 CHASSIS TIGHTENING TORQUES Item Thread Q’ty size Tightening torque Remarks Upper bracket pinch bolt M8 2 23 Nm (2.3 m·kg, 17 ft·lb) Lower bracket pinch bolt M10 2 28 Nm (2.8 m·kg, 20 ft·lb) Front brake pipe bracket bolt M6 2 7 Nm (0.7 m·kg, 5.1 ft·lb) Lower ring nut (initial tightening torque) M25 1 48 Nm (4.8 m·kg, 35 ft·lb) See NOTE. Lower ring nut (final tightening torque) M25 1 13 Nm (1.3 m·kg, 9.4 ft·lb) See NOTE.
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YamahaR125.COM Item Thread Q’ty size TIGHTENING TORQUES Tightening torque Remarks Fuel tank front bolt M6 1 10 Nm (1.0 m·kg, 7.2 ft·lb) Fuel tank rear bolt M6 2 10 Nm (1.0 m·kg, 7.2 ft·lb) Mud guard bolt M6 6 7 Nm (0.7 m·kg, 5.1 ft·lb) Passenger seat front bolt M6 1 30 Nm (3.0 m·kg, 22 ft·lb) Passenger seat rear bolt M8 1 11 Nm (1.1 m·kg, 8.0 ft·lb) Front wheel axle M14 1 59 Nm (5.9 m·kg, 43 ft·lb) Front wheel axle pinch bolt M8 1 14 Nm (1.
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YamahaR125.COM TIGHTENING TORQUES • Retighten the lower ring nut to 13 Nm (1.3 m·kg, 9.4 ft·lb) with a torque wrench.
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LUBRICATION POINTS AND LUBRICANT TYPES YamahaR125.
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LUBRICATION POINTS AND LUBRICANT TYPES YamahaR125.COM Lubrication point Lubricant Clutch push rod ball E Clutch boss nut seat and clutch boss nut thread E Main axle and pinion gears M Drive axle and wheel gears M Shift drum assembly E Shift forks and shift fork guide bar E Shift shaft E Crankshaft position sensor/stator assembly lead grommet Yamaha bond No.1215 (Three Bond No.1215®) Crankcase mating surfaces Yamaha bond No.1215 (Three Bond No.
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LUBRICATION POINTS AND LUBRICANT TYPES YamahaR125.
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LUBRICATION SYSTEM CHART AND DIAGRAMS YamahaR125.
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LUBRICATION SYSTEM CHART AND DIAGRAMS YamahaR125.COM 1. 2. 3. 4. 5. 6.
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LUBRICATION SYSTEM CHART AND DIAGRAMS YamahaR125.
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LUBRICATION SYSTEM CHART AND DIAGRAMS YamahaR125.COM 1. 2. 3. 4. 5. 6. 7. A.
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LUBRICATION SYSTEM CHART AND DIAGRAMS YamahaR125.
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LUBRICATION SYSTEM CHART AND DIAGRAMS YamahaR125.COM 1. 2. 3. 4.
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COOLING SYSTEM DIAGRAMS YamahaR125.
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YamahaR125.COM 1. 2. 3. 4. 5. 6. 7. 8. 9.
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CABLE ROUTING YamahaR125.
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YamahaR125.COM 1. Front brake light switch lead 2. Right handlebar switch lead 3. Throttle cable 4. Main switch 5. Clutch cable 6. Clutch switch lead 7. Left handlebar switch lead 8. Sub-wire harness 9. Horn 10. Speed sensor lead 11. Front brake hose 12. Main switch lead 13. Left headlight assembly lead 14. Right headlight assembly lead A. Route the right handlebar switch lead to the rear the front brake hose. B. Route the throttle cable in front of the front brake light switch lead. C.
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CABLE ROUTING YamahaR125.
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YamahaR125.COM 1. Throttle body 2. Wire harness 3. Ignition coil 4. Spark plug lead 5. Sub-wire harness 6. Front brake light switch lead 7. Throttle cable 8. Right handlebar switch lead 9. Right headlight assembly lead 10. Left headlight assembly lead 11. Front brake hose 12. Main switch lead 13. Speed sensor lead 14. Radiator inlet hose 15. Radiator fan motor lead 16. Wire harness (to coolant temperature sensor) 17. Starter motor 18. Front turn signal light lead A.
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CABLE ROUTING YamahaR125.
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YamahaR125.COM 1. 2. 3. 4. 5. A. Battery breather hose Wire harness Starter motor lead Rear brake light switch lead Rear brake hose Fasten the battery breather hose with the holder.
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CABLE ROUTING YamahaR125.
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YamahaR125.COM 1. Front brake hose 2. Throttle cable 3. Left handlebar switch lead 4. Clutch cable 5. Wire harness (to horn) 6. Ignition coil 7. Air filter case silencer hose 8. Sidestand switch lead 9. Coolant reservoir hose 10. Fuel tank breather hose 11. Coolant reservoir breather hose 12. Front left turn signal light coupler 13. Speed sensor lead 14. Wire harness (to clutch switch) 15. Front left turn signal light lead 16. Horn 17. Fuel hose 18. Fuel pump lead 19. Fuel sender lead A.
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CABLE ROUTING YamahaR125.
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YamahaR125.COM 1. Air filter case silencer hose 2. Wire harness 3. Battery 4. Lean angle sensor 5. Tail/brake light lead 6. Sidestand switch lead 7. Neutral switch 8. Crankshaft position sensor/stator coil lead 9. Negative battery lead 10. Rectifier/regulator 11. Ground lead terminal 12. Rear right turn signal light lead 13. License plate light lead 14. Rear left turn signal light lead 15. Wire harness (to neutral switch) A. Fasten the wire harness at the white tape with a plastic locking tie. B.
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CABLE ROUTING YamahaR125.
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YamahaR125.COM 1. Coolant reservoir hose 2. Radiator inlet hose 3. Spark plug lead 4. Wire harness 5. FID (fast idle solenoid) lead 6. Fuel injector lead 7. Rear brake light switch lead 8. Throttle body sensor assembly 9. Ignition coil leads 10. Air filter case silencer hose 11. Wire harness (to horn) 12. Clutch cable 13. Throttle cable 14. Wire harness (to left handlebar switch) 15. Front brake light switch lead 16. Right handlebar switch lead 17. Main switch lead 18. Cylinder head breather hose A.
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CABLE ROUTING YamahaR125.
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YamahaR125.COM 1. Positive battery lead 2. Starter relay 3. Radiator fan motor relay 4. Turn signal relay 5. Lean angle sensor 6. Rear right turn signal light lead 7. License plate light lead 8. Rear left turn signal light lead 9. Tail/brake light lead 10. Starting circuit cut-off relay 11. Headlight relay 12. ECU (engine control unit) 13. Wire harness 14. Fuse box 15. Negative battery lead 16. Battery A. Fasten the wire harness with a plastic locking tie. B.
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YamahaR125.
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YamahaR125.COM PERIODIC CHECKS AND ADJUSTMENTS PERIODIC MAINTENANCE ............................................................................ 3-1 INTRODUCTION ....................................................................................... 3-1 PERIODIC MAINTENANCE AND LUBRICATION CHART....................... 3-1 ENGINE ........................................................................................................... 3-3 ADJUSTING THE VALVE CLEARANCE .......................................
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YamahaR125.COM ELECTRICAL SYSTEM................................................................................. 3-27 CHECKING AND CHARGING THE BATTERY....................................... 3-27 CHECKING THE FUSES ........................................................................ 3-27 REPLACING THE HEADLIGHT BULBS ................................................. 3-27 ADJUSTING THE HEADLIGHT BEAMS.................................................
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YamahaR125.
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PERIODIC MAINTENANCE YamahaR125.COM EAS20450 PERIODIC MAINTENANCE EAS20460 INTRODUCTION This chapter includes all information necessary to perform recommended checks and adjustments. If followed, these preventive maintenance procedures will ensure more reliable vehicle operation, a longer service life and reduce the need for costly overhaul work. This information applies to vehicles already in service as well as to new vehicles that are being prepared for sale.
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PERIODIC MAINTENANCE YamahaR125.COM NO.
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ENGINE YamahaR125.COM EAS20471 ENGINE EAS20520 ADJUSTING THE VALVE CLEARANCE The following procedure applies to all of the valves. 1 NOTE: 2 • Valve clearance adjustment should be made on a cold engine, at room temperature. • When the valve clearance is to be measured or adjusted, the piston must be at top dead center (TDC) on the compression stroke. 6. Measure: • Valve clearance Out of specification → Adjust. 1. Remove: • Bottom cowling Refer to “GENERAL CHASSIS” on page 4-1.
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ENGINE YamahaR125.COM • Hold the adjusting screw to prevent it from moving and tighten the locknut to specification. 1 T. R. Valve adjusting screw locknut 7 Nm (0.7 m·kg, 5.1 ft·lb) d. Measure the valve clearance again. e. If the valve clearance is still out of specification, repeat all of the valve clearance adjustment steps until the specified clearance is obtained. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 7. Adjust: • Valve clearance ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 8.
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ENGINE YamahaR125.COM 3 3 2 1 FI Diagnostic Tool 2 DIAG 1 4 1 4 6. Press the “UP” button “4” to select the CO adjustment mode “CO” or the diagnostic mode “DIAG”. 7. After selecting “CO”, press the “MODE” button. 8. Check that “C1” appears on the LCD of the FI diagnostic tool, and then press the “MODE” button. 9. Start the engine. 13.Connect: • Spark plug cap 14.Install: • Fuel tank Refer to “FUEL TANK” on page 7-1. • Bottom cowling Refer to “GENERAL CHASSIS” on page 4-1.
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ENGINE YamahaR125.COM 8. Remove: • Digital tachometer 9. Install: • Fuel tank Refer to “FUEL TANK” on page 7-1. • Right side panel • Rider seat Refer to “GENERAL CHASSIS” on page 4-1. 10.Adjust: • Throttle cable free play Refer to “ADJUSTING THE THROTTLE CABLE FREE PLAY” on page 3-6. 15.Install: • Rider seat Refer to “GENERAL CHASSIS” on page 4-1.
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ENGINE YamahaR125.COM EWA12930 WARNING Direction “a” Throttle cable free play is increased. Direction “b” Throttle cable free play is decreased. After adjusting the throttle cable free play, start the engine and turn the handlebar to the right or left to ensure that this does not cause the engine idling speed to change. c. Tighten the locknut. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ T. R. Throttle cable locknut 7 Nm (0.7 m·kg, 5.1 ft·lb) 4.
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ENGINE YamahaR125.COM • Digital tachometer Timing light 90890-03141 Inductive clamp timing light YU-03141 8. Install: • Spark plug T. R. Spark plug 13 Nm (1.3 m·kg, 9.4 ft·lb) 1 NOTE: 5. Check: • Ignition timing Before installing the spark plug, clean the spark plug and gasket surface. ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Start the engine, warm it up for several minutes, and then let it run at the specified engine idling speed. 9. Connect: • Spark plug cap 10.
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ENGINE YamahaR125.COM 8. Install: • Timing mark accessing screw • Compression gauge “2” Extension 90890-04082 Compression gauge 90890-03081 Engine compression tester YU-33223 (along with the O-ring New ) 9. Install: • Left lower side cowling • Right side cover • Rider seat Refer to “GENERAL CHASSIS” on page 4-1. 2 EAS20710 MEASURING THE COMPRESSION PRESSURE 1 NOTE: Insufficient compression pressure will result in a loss of performance. 1. Measure: • Valve clearance Out of specification → Adjust.
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ENGINE YamahaR125.COM Compression pressure (with oil applied into the cylinder) Reading Diagnosis Higher than without oil Piston ring(s) wear or damage → Repair. Same as without oil Piston, valves, cylinder head gasket or piston possibly defective → Repair. 1 1 b a Type SAE 10W-30, SAE 10W-40, SAE 15W-40, SAE 20W-40 or SAE 20W-50 Recommended engine oil grade API service SG type or higher, JASO standard MA ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 9. Remove: • Extension • Compression gauge 10.
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ENGINE YamahaR125.COM 4. Start the engine, warm it up for several minutes, and then turn it off. 5. Check the engine oil level again. NOTE: Before checking the engine oil level, wait a few minutes until the oil has settled. 5 4 3 2 EAS20810 CHANGING THE ENGINE OIL 1. Remove: • Right bottom cowling • Right upper side cowling • Right lower side cowling Refer to “GENERAL CHASSIS” on page 4-1. 2. Start the engine, warm it up for several minutes, and then turn it off. 3.
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ENGINE YamahaR125.COM • Right bottom side cowling Refer to “GENERAL CHASSIS” on page 4-1. Engine oil quantity Total amount 1.15 L (1.22 US qt) (1.01 Imp.qt) Without oil filter element replacement 0.95 L (1.00 US qt) (0.84 Imp.qt) With oil filter element replacement 1.00 L (1.06 US qt) (0.88 Imp.qt) EAS20870 ADJUSTING THE CLUTCH CABLE FREE PLAY 1. Check: • Clutch cable free play “a” Out of specification → Adjust. Clutch lever free play 10.0–15.0 mm (0.39–0.59 in) 11.Install: • Engine oil filler cap 12.
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ENGINE YamahaR125.COM NOTE: If the specified clutch cable free play cannot be obtained on the handlebar end of the cable, use the adjusting nut on the engine end. 1 ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 3. Remove: • Left lower side cowling Refer to “GENERAL CHASSIS” on page 4-1. 1. Remove: • Rider seat Refer to “GENERAL CHASSIS” on page 4-1. 2. Remove: • Fuel tank Refer to “FUEL TANK” on page 7-1. 3. Remove: • Air filter case cover “1” • Air filter element ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ Engine end a.
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ENGINE YamahaR125.COM 2. Lift the fuel tank. (Do not disconnect the fuel hose, drain hose, and couplers.) 3. Check: • Fuel hose “1” Cracks/damage → Replace. Loose connection → Connect properly. ECA5D71025 CAUTION: Never operate the engine without the air filter element installed. Unfiltered air will cause rapid wear of engine parts and may damage the engine.
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ENGINE YamahaR125.COM EAS21080 ECA5D71035 CHECKING THE EXHAUST SYSTEM 1. Check: • Exhaust assembly “1” Cracks/damage → Replace. • Exhaust pipe gasket “2” Exhaust gas leaks → Replace. 2. Check: • Tightening torques of the exhaust pipe nuts “3” and exhaust assembly bolts “4” CAUTION: • Adding water instead of coolant lowers the antifreeze content of the coolant. If water is used instead of coolant, check and, if necessary, correct the antifreeze concentration of the coolant. • Use only distilled water.
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ENGINE YamahaR125.COM 2. Remove: • Radiator cap “1” 2 1 1 7. Drain: • Coolant (from the coolant reservoir) 8. Connect: • Coolant reservoir hose 9. Install: • Coolant drain bolt EWA13030 WARNING A hot radiator is under pressure. Therefore, do not remove the radiator cap when the engine is hot. Scalding hot fluid and steam may be blown out, which could cause serious injury.
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YamahaR125.COM ECA5D71036 CAUTION: • Adding water instead of coolant lowers the antifreeze content of the coolant. If water is used instead of coolant, check and, if necessary, correct the antifreeze concentration of the coolant. • Use only distilled water. However, if distilled water is not available, soft water may be used. • If coolant comes into contact with painted surfaces, immediately wash them with water. • Do not mix different types of antifreeze. 11.Install: • Radiator cap 12.
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CHASSIS YamahaR125.COM EAS21140 EWA5D71014 CHASSIS WARNING A soft or spongy feeling in the brake pedal can indicate the presence of air in the brake system. Before the vehicle is operated, the air must be removed by bleeding the brake system. Air in the brake system will considerably reduce braking performance. EAS21200 ADJUSTING THE REAR DISC BRAKE 1. Check: • Brake pedal position (distance “a” from the center of the rider footrest to the center of the brake pedal) Out of specification → Adjust.
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CHASSIS YamahaR125.COM 1. Operate the brake. 2. Check: • Front brake pad Wear indicator grooves “a” have almost disappeared → Replace the brake pads as a set. Refer to “FRONT BRAKE” on page 4-17. A a a B a EAS21260 A. Front brake B. Rear brake EWA13090 WARNING • Use only the designated brake fluid. Other brake fluids may cause the rubber seals to deteriorate, causing leakage and poor brake performance. • Refill with the same type of brake fluid that is already in the system.
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CHASSIS YamahaR125.COM • the brake fluid level is very low. • brake operation is faulty. NOTE: • Be careful not to spill any brake fluid or allow the brake master cylinder reservoir or brake fluid reservoir to overflow. • When bleeding the hydraulic brake system, make sure there is always enough brake fluid before applying the brake. Ignoring this precaution could allow air to enter the hydraulic brake system, considerably lengthening the bleeding procedure.
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CHASSIS YamahaR125.COM 2. Turn the rear wheel several times and find the tightest position on the drive chain. 3. Check: • Drive chain slack “a” Out of specification → Adjust. f. Fully pull the brake lever or fully press down the brake pedal and hold it in position. g. Loosen the bleed screw. NOTE: Loosening the bleed screw will release the pressure and cause the brake lever to contact the throttle grip or the brake pedal to fully extend. h.
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CHASSIS YamahaR125.COM d. Tighten the wheel axle nut to specification. 4. Adjust: • Steering head T. R. Wheel axle nut 85 Nm (8.5 m·kg, 61 ft·lb) ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Remove the lock washer “1”, the upper ring nut “2”, and the rubber washer “3”. e. Tighten the locknuts to specification. T. R. Drive chain adjusting locknut 16 Nm (1.6 m·kg, 11 ft·lb) ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ EAS21440 LUBRICATING THE DRIVE CHAIN The drive chain consists of many interacting parts.
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CHASSIS YamahaR125.COM d. Check the steering head for looseness or binding by turning the front fork all the way in both directions. If any binding is felt, remove the lower bracket and check the upper and lower bearings. Refer to “STEERING HEAD” on page 4-52. e. Install the rubber washer “3”. f. Install the upper ring nut “2”. g. Finger tighten the upper ring nut “2”, and then align the slots of both ring nuts.
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CHASSIS YamahaR125.COM • When using a tube tire, be sure to install the correct tube. • Always replace a new tube tire and a new tube as a set. • To avoid pinching the tube, make sure the wheel rim band and tube are centered in the wheel groove. • Patching a punctured tube is not recommended. If it is absolutely necessary to do so, use great care and replace the tube as soon as possible with a good quality replacement.
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CHASSIS YamahaR125.COM EWA13270 WARNING Rear tire Size 130/70–17 M/C 62H Manufacturer/model PIRELLI/SPORT DEMON Manufacturer/model MICHELIN/PILOT SPORTY Damaged outer cable may cause the cable to corrode and interfere with its movement. Replace damaged outer cable and inner cables as soon as possible. 1. Check: • Outer cable Damage → Replace. 2. Check: • Cable operation Rough movement → Lubricate.
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YamahaR125.COM EAS21740 LUBRICATING THE REAR SUSPENSION Lubricate the pivoting point and metal-to-metal moving parts of the rear suspension.
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ELECTRICAL SYSTEM YamahaR125.COM EAS21750 EWA13320 ELECTRICAL SYSTEM WARNING Since the headlight bulb gets extremely hot, keep flammable products and your hands away from the bulb until it has cooled down. EAS21760 CHECKING AND CHARGING THE BATTERY Refer to “ELECTRICAL COMPONENTS” on page 8-57. 4. Install: • Headlight bulb New Secure the new headlight bulb with the headlight bulb holder. EAS21770 CHECKING THE FUSES Refer to “ELECTRICAL COMPONENTS” on page 8-57.
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ELECTRICAL SYSTEM YamahaR125.COM ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Turn the adjusting screw “1” in direction “a” or “b”. Direction “a” Headlight beam is lowered. Direction “b” Headlight beam is raised. 1 A 4. Remove: • Headlight bulb “1” a b 1 1 B a EWA13320 WARNING b Since the headlight bulb gets extremely hot, keep flammable products and your hands away from the bulb until it has cooled down. 1 5. Install: A. Left headlight B.
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YamahaR125.
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YamahaR125.COM CHASSIS GENERAL CHASSIS....................................................................................... 4-1 INSTALLING THE AIR FILTER CASE ...................................................... 4-5 FRONT WHEEL............................................................................................... 4-6 REMOVING THE FRONT WHEEL (DISC)................................................ 4-8 DISASSEMBLING THE FRONT WHEEL..................................................
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YamahaR125.COM HANDLEBARS .............................................................................................. 4-39 REMOVING THE HANDLEBARS ........................................................... 4-41 CHECKING THE HANDLEBARS ............................................................ 4-41 INSTALLING THE HANDLEBARS .......................................................... 4-41 FRONT FORK................................................................................................
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YamahaR125.
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GENERAL CHASSIS YamahaR125.COM EAS21830 GENERAL CHASSIS Removing the seats and battery T. 30 Nm (3.0 m • kg, 22 ft • Ib) R. T. R. 11 Nm (1.1 m • kg, 8.0 ft • Ib) 1 2 5 4 3 6 Order 7 Job/Parts to remove 1 Rider seat Q’ty Remarks 1 2 Passenger seat 1 3 Negative battery lead 1 Disconnect. 4 Positive battery lead 1 Disconnect. 5 Battery band 1 6 Battery 1 7 Battery breather hose 1 Disconnect. For installation, reverse the removal procedure.
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GENERAL CHASSIS YamahaR125.COM Removing the rear side cowlings R. R. 3 T. T. 7 Nm (0.7 m • kg, 5.1 ft • Ib) 7 Nm (0.7 m • kg, 5.1 ft • Ib) 2 1 3 1 Order Job/Parts to remove Q’ty Remarks Refer to “GENERAL CHASSIS” on page 4-1. Rider seat/Passenger seat 1 Side panel 2 2 Rear panel 1 3 Rear side cowling 2 For installation, reverse the removal procedure.
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GENERAL CHASSIS YamahaR125.COM Removing the side cowlings and front cowling assembly T. R. 6 23 Nm (2.3 m • kg, 17 ft • Ib) 1 8 2 9 7 8 3 4 3 10 2 5 1 5 Order 4 Job/Parts to remove Q’ty Remarks Refer to “GENERAL CHASSIS” on page 4-1.
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GENERAL CHASSIS YamahaR125.COM Removing the air filter case 1 5 3 8 2 3 4 T. R. 2 Nm (0.2 m • kg, 1.4 ft • Ib) 6 7 T. R. Order Job/Parts to remove 10 Nm (1.0 m • kg, 7.2 ft • Ib) Q’ty Remarks Fuel tank cover Refer to “GENERAL CHASSIS” on page 4-1. Fuel tank Refer to “FUEL TANK” on page 7-1. 1 Air filter case cover 1 2 Air filter element 1 3 Air filter case seal 2 4 Air filter case joint clamp screw 1 Loosen.
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YamahaR125.COM EAS5D71027 INSTALLING THE AIR FILTER CASE 1. Install: • Air filter case joint clamp NOTE: Align the projection “a” on the air filter case with the slot “b” in the air filter case joint clamp.
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FRONT WHEEL YamahaR125.COM EAS21870 FRONT WHEEL Removing the front wheel and brake disc T. T. R. R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) 7 Nm (0.7 m • kg, 5.1 ft • Ib) 9 T. R. 59 Nm (5.9 m • kg, 43 ft • Ib) 4 1 LS T. R. 14 Nm (1.4 m • kg, 10 ft • Ib) LS 3 LT 2 T. R. 30 Nm (3.0 m • kg, 22 ft • Ib) 8 6 7 (5) T. 5 LT R. Order Job/Parts to remove Q’ty 18 Nm (1.8 m • kg, 13 ft • Ib) Remarks NOTE: Place the vehicle on a suitable stand so that the front wheel is elevated.
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FRONT WHEEL YamahaR125.COM Disassembling the front wheel 4 3 2 1 New LS Order Job/Parts to remove Q’ty 1 Oil seal 2 Bearing 1 3 Spacer 1 4 Bearing 1 Remarks 1 For assembly, reverse the disassembly procedure.
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FRONT WHEEL YamahaR125.COM EAS21890 REMOVING THE FRONT WHEEL (DISC) 1. Stand the vehicle on a level surface. EWA13120 WARNING Securely support the vehicle so that there is no danger of it falling over. 2. Elevate: • Front wheel NOTE: Place the vehicle on a suitable stand so that the front wheel is elevated. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ EAS21920 CHECKING THE FRONT WHEEL 1. Check: • Front wheel axle Roll the wheel axle on a flat surface. Bends → Replace. 3.
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FRONT WHEEL YamahaR125.COM 4. Check: • Wheel bearings Front wheel turns roughly or is loose → Replace the wheel bearings. • Oil seal Damage/wear → Replace. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ EAS21970 ADJUSTING THE FRONT WHEEL STATIC BALANCE NOTE: • After replacing the tire, wheel or both, the front wheel static balance should be adjusted. • Adjust the front wheel static balance with the brake discs installed. 1. Remove: • Balancing weight(s) 2.
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FRONT WHEEL YamahaR125.COM ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Turn the front wheel and make sure it stays at each position shown. f. Repeat steps (c) through (e) several times until all the marks come to rest at the same spot. g. The spot where all the marks come to rest is the front wheel’s heavy spot “X”. b. If the front wheel does not remain stationary at all of the positions, rebalance it. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 3.
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FRONT WHEEL YamahaR125.COM 3. Lubricate: • Front wheel axle • Oil seal lip • Speed sensor lip ECA5D71028 CAUTION: Before tightening the wheel axle, push down hard on the handlebar(s) several times and check if the front fork rebounds smoothly. Recommended lubricant Lithium-soap-based grease ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Insert the front wheel axle from the right side and tighten it from the left side to 59 Nm (5.9 m·kg, 43 ft·lb) without performing temporary tightening. b.
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REAR WHEEL YamahaR125.COM EAS22020 REAR WHEEL Removing the rear wheel 7 8 T. R. 85 Nm (8.5 m • kg, 61 ft • Ib) 4 6 9 LT T. R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) 1 3 6 2 T. R. Order 7 Nm (0.7 m • kg, 5.1 ft • Ib) Job/Parts to remove Q’ty 5 Remarks NOTE: Place the vehicle on a suitable stand so that the rear wheel is elevated. 1 Drive chain guard 1 2 Drive chain adjusting locknut 2 Loosen. 3 Drive chain adjusting bolt 2 Loosen.
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REAR WHEEL YamahaR125.COM Removing the brake disc and rear wheel sprocket T. R. 18 Nm (1.8 m • kg, 13 ft • Ib) LT (5) T. R. 43 Nm (4.3 m • kg, 31 ft • Ib) 1 (6) 6 7 4 5 LS New 3 LS 2 Order 1 Job/Parts to remove Q’ty Rear brake disc Remarks 1 2 Rear wheel sprocket 1 3 Oil seal 1 4 Bearing 1 5 Rear wheel drive hub 1 6 Collar 1 7 Rear wheel drive hub damper 4 For installation, reverse the removal procedure.
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REAR WHEEL YamahaR125.COM Disassembling the rear wheel New LS 3 4 2 Order 1 Job/Parts to remove Q’ty Bearing 1 Remarks 1 2 Spacer 1 3 Oil seal 1 4 Bearing 1 For assembly, reverse the disassembly procedure.
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REAR WHEEL YamahaR125.COM Refer to “CHECKING THE TIRES” on page 3-23 and “CHECKING THE WHEELS” on page 3-25. 3. Measure: • Radial wheel runout • Lateral wheel runout Refer to “CHECKING THE FRONT WHEEL” on page 4-8. EAS22040 REMOVING THE REAR WHEEL (DISC) 1. Stand the vehicle on a level surface. EWA13120 WARNING Securely support the vehicle so that there is no danger of it falling over. 2. Elevate: • Rear wheel Radial wheel runout limit 0.5 mm (0.02 in) Lateral wheel runout limit 1.0 mm (0.
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REAR WHEEL YamahaR125.COM ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ T. R. a. Remove the self-locking nuts and the rear wheel sprocket. b. Clean the rear wheel drive hub with a clean cloth, especially the surfaces that contact the sprocket. c. Install the new rear wheel sprocket. Rear brake disc bolt 18 Nm (1.8 m·kg, 13 ft·lb) LOCTITE® NOTE: Tighten the brake disc bolts in stages and in a crisscross pattern. T. R. Rear wheel sprocket self-locking nut 43 Nm (4.
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FRONT BRAKE YamahaR125.COM EAS22210 FRONT BRAKE Removing the front brake pads T. R. 30 Nm (3.0 m • kg, 22 ft • Ib) T. R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) LT 2 1 4 5 8 7 3 1 R. Order T. 6 Job/Parts to remove Q’ty Brake hose holder 14 Nm (1.
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FRONT BRAKE YamahaR125.COM Removing the front brake master cylinder 1 T. R. 30 Nm (3.0 m • kg, 22 ft • Ib) 3 T. R. 4 9 Nm (0.9 m • kg, 6.5 ft • Ib) 2 6 S New 5 8 7 9 Order Job/Parts to remove Q’ty Remarks Drain. Refer to “BLEEDING THE HYDRAULIC BRAKE SYSTEM” on page 3-20.
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FRONT BRAKE YamahaR125.COM Removing the front brake caliper T. R. 30 Nm (3.0 m • kg, 22 ft • Ib) T. R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) 1 4 5 2 LT 3 New Job/Parts to remove Q’ty R. Order T. 6 30 Nm (3.0 m • kg, 22 ft • Ib) Remarks Drain. Refer to “BLEEDING THE HYDRAULIC BRAKE SYSTEM” on page 3-20.
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FRONT BRAKE YamahaR125.COM Disassembling the front brake caliper 7 S 5 6 S 4 1 1 3 Order 2 Job/Parts to remove Q’ty 1 Brake pad clip 2 Brake pad pin 1 3 Brake pad 2 4 Brake pad spring 1 5 Brake caliper bracket 1 6 Brake pad support 1 7 Brake caliper body 1 Remarks 2 For assembly, reverse the disassembly procedure.
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FRONT BRAKE YamahaR125.COM EAS22220 ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ INTRODUCTION a. Place the vehicle on a suitable stand so that the front wheel is elevated. b. Before measuring the front brake disc deflection, turn the handlebar to the left or right to ensure that the front wheel is stationary. c. Remove the brake caliper. d. Hold the dial gauge at a right angle against the brake disc surface. e. Measure the deflection 1.5 mm (0.06 in) below the edge of the brake disc.
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FRONT BRAKE YamahaR125.COM 2. Install: • Brake pad support New • Brake pad spring New • Brake pads New NOTE: Always install new brake pads, a new brake pad spring and a new brake pad support as a set. ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Connect a clear plastic hose “1” tightly to the bleed screw “2”. Put the other end of the hose into an open container. d. Measure the brake disc deflection. e. If out of specification, repeat the adjustment steps until the brake disc deflection is within specification.
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FRONT BRAKE YamahaR125.COM EAS22380 CHECKING THE FRONT BRAKE CALIPER T. R. Front brake caliper bolt 30 Nm (3.0 m·kg, 22 ft·lb) LOCTITE® Recommended brake component replacement schedule 4. Check: • Brake fluid level Below the minimum level mark “a” → Add the recommended brake fluid to the proper level. Refer to “CHECKING THE BRAKE FLUID LEVEL” on page 3-18.
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FRONT BRAKE YamahaR125.COM T. • Whenever a brake caliper is disassembled, replace the brake caliper dust seals and piston seals. R. Recommended fluid DOT 4 Front brake caliper bolt 30 Nm (3.0 m·kg, 22 ft·lb) LOCTITE® Front brake hose holder 7 Nm (0.7 m·kg, 5.1 ft·lb) Refer to “REPLACING THE FRONT BRAKE PADS” on page 4-22. 4. Fill: • Brake master cylinder reservoir (with the specified amount of the recommended brake fluid) EAS22420 INSTALLING THE FRONT BRAKE CALIPER 1.
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FRONT BRAKE YamahaR125.COM 3. Check: • Brake hose Cracks/damage/wear → Replace. a EAS22520 ASSEMBLING THE FRONT BRAKE MASTER CYLINDER EWA13520 WARNING • Before installation, all internal brake components should be cleaned and lubricated with clean or new brake fluid. • Never use solvents on internal brake components. 7. Check: • Brake lever operation Soft or spongy feeling → Bleed the brake system. Refer to “BLEEDING THE HYDRAULIC BRAKE SYSTEM” on page 3-20.
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FRONT BRAKE YamahaR125.COM NOTE: Before fully installing the front brake light switch, be sure to completely install the rubber cover over the switch. Also, be sure not to twist the front brake light switch lead when screwing in the switch. FWD 4. Fill: • Brake master cylinder reservoir (with the specified amount of the recommended brake fluid) 2. Install: Recommended fluid DOT 4 • Copper washers “1” New • Brake hose “2” • Brake hose union bolt “3” • Front brake light switch EWA13540 WARNING T.
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YamahaR125.COM a 7. Check: • Brake lever operation Soft or spongy feeling → Bleed the brake system. Refer to “BLEEDING THE HYDRAULIC BRAKE SYSTEM” on page 3-20.
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REAR BRAKE YamahaR125.COM EAS22550 REAR BRAKE Removing the rear brake pads 1 T. R. 14 Nm (1.4 m • kg, 10 ft • Ib) 4 2 2 LT 3 T. R. Order LT Job/Parts to remove Q’ty Rear wheel 18 Nm (1.8 m • kg, 13 ft • Ib) Remarks Refer to “REAR WHEEL” on page 4-12. 1 Rear brake caliper 1 2 Brake pad retaining bolt 2 3 Rear brake pad 2 4 Brake pad spring 1 For installation, reverse the removal procedure.
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REAR BRAKE YamahaR125.COM Removing the rear brake master cylinder 7 2 3 4 5 6 1 10 12 11 New 9 T. R. 24 Nm (2.4 m • kg, 17 ft • Ib) 8 New R. Job/Parts to remove T. Order 8 13 Nm (1.3 m • kg, 9.4 ft • Ib) Q’ty Remarks Right side panel Refer to “GENERAL CHASSIS” on page 4-1. Brake fluid Drain. Refer to “BLEEDING THE HYDRAULIC BRAKE SYSTEM” on page 3-20.
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REAR BRAKE YamahaR125.COM Disassembling the rear brake master cylinder New T. R. 17 Nm (1.7 m • kg, 12 ft • Ib) 1 New S 3 2 New Order Job/Parts to remove Q’ty 1 Brake hose joint 2 Brake master cylinder kit 1 3 Brake master cylinder body 1 Remarks 1 For assembly, reverse the disassembly procedure.
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REAR BRAKE YamahaR125.COM Removing the rear brake caliper T. R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) T. R. 30 Nm (3.0 m • kg, 22 ft • Ib) 1 New 2 3 4 Order Job/Parts to remove Q’ty Remarks Brake fluid Drain. Refer to “BLEEDING THE HYDRAULIC BRAKE SYSTEM” on page 3-20. Rear wheel Refer to “REAR WHEEL” on page 4-12. 1 Rear brake hose union bolt 1 2 Copper washer 2 3 Rear brake hose 1 4 Rear brake caliper 1 For installation, reverse the removal procedure.
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REAR BRAKE YamahaR125.COM Disassembling the rear brake caliper 6 New S 7 New 5 BF 2 S 4 S 1 8 1 T. R. 14 Nm (1.4 m • kg, 10 ft • Ib) Q’ty Brake pad retaining bolt R. 1 Job/Parts to remove T. Order 3 18 Nm (1.8 m • kg, 13 ft • Ib) Remarks 2 2 Rear brake pad 2 3 Brake pad spring 1 4 Brake caliper bracket 1 5 Brake caliper piston 1 6 Brake caliper piston dust seal 1 7 Brake caliper piston seal 1 8 Bleed screw 1 For assembly, reverse the disassembly procedure.
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REAR BRAKE YamahaR125.COM EAS22560 INTRODUCTION Brake disc thickness limit 3.5 mm (0.14 in) EWA14100 WARNING 5. Adjust: • Brake disc deflection Refer to “CHECKING THE FRONT BRAKE DISC” on page 4-21. T. R. Disc brake components rarely require disassembly. Therefore, always follow these preventive measures: • Never disassemble brake components unless absolutely necessary.
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REAR BRAKE YamahaR125.COM Brake pad lining thickness (inner) 5.5 mm (0.22 in) Limit 1.0 mm (0.04 in) Brake pad lining thickness (outer) 5.5 mm (0.22 in) Limit 1.0 mm (0.04 in) NOTE: Install the brake pad spring as shown. 1 ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 4. Install: • Brake pad retaining bolts • Brake caliper T. R. 3. Install: Rear brake pad retaining bolt 18 Nm (1.8 m·kg, 13 ft·lb) LOCTITE® 5. Install: • Rear wheel Refer to “REAR WHEEL” on page 4-12. 6.
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REAR BRAKE YamahaR125.COM 1. Remove: • Union bolt “1” • Copper washers “2” • Brake hose “3” a 2 3 b. Remove the brake caliper piston seal and dust seal. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 1 EAS22640 CHECKING THE REAR BRAKE CALIPER NOTE: Recommended brake component replacement schedule Put the end of the brake hose into a container and pump out the brake fluid carefully. EAS22600 DISASSEMBLING THE REAR BRAKE CALIPER 1.
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REAR BRAKE YamahaR125.COM EWA5D71012 WARNING Whenever a brake caliper is disassembled, replace the brake caliper piston dust seals and piston seals. 3 2. Check: • Brake caliper bracket Cracks/damage → Replace. 2 a b 1 EAS22650 ASSEMBLING THE REAR BRAKE CALIPER 2. Install: • Brake pad spring • Brake pads • Brake pad retaining bolts • Rear brake caliper Refer to “REPLACING THE REAR BRAKE PADS” on page 4-33. EWA5D71017 WARNING T.
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REAR BRAKE YamahaR125.COM 5. Bleed: • Brake system Refer to “BLEEDING THE HYDRAULIC BRAKE SYSTEM” on page 3-20. 6. Check: • Brake fluid level Below the minimum level mark “a” → Add the recommended brake fluid to the proper level. Refer to “CHECKING THE BRAKE FLUID LEVEL” on page 3-18. 1 3 2 NOTE: To collect any remaining brake fluid, place a container under the master cylinder and the end of the brake hose. a EAS22720 CHECKING THE REAR BRAKE MASTER CYLINDER 1.
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REAR BRAKE YamahaR125.COM EAS22740 ECA13540 INSTALLING THE REAR BRAKE MASTER CYLINDER 1. Install: CAUTION: Brake fluid may damage painted surfaces and plastic parts. Therefore, always clean up any spilt brake fluid immediately. • Copper washers “1” New • Brake hose “2” • Rear brake light switch “3” T. R. 3. Bleed: • Brake system Refer to “BLEEDING THE HYDRAULIC BRAKE SYSTEM” on page 3-20. 4.
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HANDLEBARS YamahaR125.COM EAS22850 HANDLEBARS Removing the handlebars T. R. 9 Nm (0.9 m • kg, 6.5 ft • Ib) LS 1 R. R. 26 Nm (2.6 m • kg, 19 ft • Ib) T. T. 7 8 5 4 2 9 Nm (0.9 m • kg, 6.5 ft • Ib) 14 LS 15 3 6 4 13 T. R. 9 Nm (0.9 m • kg, 6.5 ft • Ib) 10 16 16 17 LS 17 12 10 19 9 20 18 18 LS 11 LS R. R. Order T. T. 23 Nm (2.
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HANDLEBARS YamahaR125.COM Removing the handlebars T. R. 9 Nm (0.9 m • kg, 6.5 ft • Ib) LS 1 R. R. 26 Nm (2.6 m • kg, 19 ft • Ib) T. T. 7 8 5 4 2 9 Nm (0.9 m • kg, 6.5 ft • Ib) 14 LS 15 3 6 4 13 T. R. 9 Nm (0.9 m • kg, 6.5 ft • Ib) 10 16 16 17 LS 17 12 10 19 9 20 18 18 LS 11 LS R. R. Order T. T. 23 Nm (2.3 m • kg, 17 ft • Ib) Job/Parts to remove Q’ty 17 Handlebar bolt 18 Handlebar pinch bolt 2 19 Left handlebar 1 20 Right handlebar 1 26 Nm (2.
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HANDLEBARS YamahaR125.COM • Align the mating surfaces of the brake master cylinder holder with the punch mark “b” on the handlebar. • First, tighten the front bolt, then the rear bolt. EAS22870 REMOVING THE HANDLEBARS 1. Stand the vehicle on a level surface. EWA13120 WARNING Securely support the vehicle so that there is no danger of it falling over. 1 2.
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HANDLEBARS YamahaR125.COM NOTE: 2 a Align the projection “a” on the clutch switch with the slit “b” in the clutch lever holder. 1 b b 1 2 5. Install: • Right grip end “1” a NOTE: There should be 1–3 mm (0.04–0.12 in) of clearance “a” between the throttle grip and the right grip end. 8. Connect: • Clutch cable NOTE: Lubricate the end of the clutch cable with a thin coat of lithium-soap-based grease. 9.
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YamahaR125.COM NOTE: There should be 3 mm (0.12 in) of clearance “a” between the handlebar grip and the grip end. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 12.Check: • Cable routing NOTE: Make sure the main switch lead, brake hose, throttle cable, clutch cable, and handlebar switch leads are routed properly. Refer to “CABLE ROUTING” on page 2-33. 13.Adjust: • Clutch lever free play Refer to “ADJUSTING THE CLUTCH CABLE FREE PLAY” on page 3-12. Clutch lever free play 10.0–15.0 mm (0.39–0.59 in) 14.
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FRONT FORK YamahaR125.COM EAS22950 FRONT FORK Removing the front fork legs T. 2 3 R. 9 Nm (0.9 m • kg, 6.5 ft • Ib) T. R. 5 23 Nm (2.3 m • kg, 17 ft • Ib) 4 6 T. R. 28 Nm (2.8 m • kg, 20 ft • Ib) 1 LT 7 (4) T. R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) Order Job/Parts to remove Q’ty Remarks The following procedure applies to both of the front fork legs. Front wheel Refer to “FRONT WHEEL” on page 4-6. 1 Front fender 1 2 Plug 1 3 Handlebar bolt 1 Loosen.
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FRONT FORK YamahaR125.COM Disassembling the front fork legs 1 2 New 3 4 New 8 New 9 New 5 15 New 16 6 17 New 13 7 18 12 14 11 New Job/Parts to remove Q’ty R. Order T. 10 28 Nm (2.8 m • kg, 20 ft • Ib) Remarks The following procedure applies to both of the front fork legs.
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FRONT FORK YamahaR125.COM Disassembling the front fork legs 1 2 New 3 4 New 8 New 9 New 5 15 New 16 6 17 New 13 7 18 12 14 11 New Job/Parts to remove Q’ty 17 Outer tube bushing 1 18 Outer tube 1 R. Order T. 10 28 Nm (2.8 m • kg, 20 ft • Ib) Remarks For assembly, reverse the disassembly procedure.
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FRONT FORK YamahaR125.COM EAS22960 REMOVING THE FRONT FORK LEGS The following procedure applies to both of the front fork legs. 1. Stand the vehicle on a level surface. NOTE: Push the front fork cap in the direction of the arrow shown in the illustration to remove the clip. EWA13120 1 WARNING 1 Securely support the vehicle so that there is no danger of it falling over. 2 2.
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FRONT FORK YamahaR125.COM NOTE: While holding the damper rod with the damper rod holder “2” and T-handle “3”, loosen the damper rod bolt. Damper rod holder 90890-01294 Damping rod holder set YM-01300 T-handle 90890-01326 T-handle 3/8" drive 60 cm long YM-01326 3. Check: • Damper rod Damage/wear → Replace. Obstruction → Blow out all of the oil passages with compressed air. • Oil flow stopper Damage → Replace.
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FRONT FORK YamahaR125.COM Recommended oil Fork oil 10W or equivalent 3. Tighten: • Damper rod bolt “1” T. R. Damper rod bolt 28 Nm (2.8 m·kg, 20 ft·lb) NOTE: 5. Install: While holding the damper rod with the damper rod holder “2” and T-handle “3”, tighten the damper rod bolt.
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FRONT FORK YamahaR125.COM Recommended oil Fork oil 10W or equivalent Quantity 235.0 cm³ (7.95 US oz) (8.29 Imp.oz) ECA14230 CAUTION: • Be sure to use the recommended fork oil. Other oils may have an adverse effect on front fork performance. • When disassembling and assembling the front fork leg, do not allow any foreign material to enter the front fork. 6. Install: • Oil seal clip “1” New NOTE: Adjust the oil seal clip so that it fits into the outer tube’s groove. 9.
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FRONT FORK YamahaR125.COM a 12.Install: • Fork spring “1” 2. Tighten: • Lower bracket pinch bolt “1” NOTE: T. Install the spring with the smaller pitch “a” facing up. R. Lower bracket pinch bolt 28 Nm (2.8 m·kg, 20 ft·lb) • Upper bracket pinch bolt “2” T. R. a Upper bracket pinch bolt 23 Nm (2.3 m·kg, 17 ft·lb) • Handlebar bolt “3” 1 T. R. Handlebar bolt 9 Nm (0.9 m·kg, 6.5 ft·lb) • Handlebar pinch bolt “4” 13.Install: T. • O-ring New (to front fork cap) • Front fork cap R.
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STEERING HEAD YamahaR125.COM EAS23090 STEERING HEAD Removing the lower bracket T. R. 110 Nm (11.0 m • kg, 80 ft • lb) 2 3 14 12 4 5 LS 15 LS 6 7 9 New 16 8 T. R. 10 11 13 11 Nm (1.1 m • kg, 8.0 ft • Ib) 1 R. R. Order T. T. 7 Nm (0.7 m • kg, 5.1 ft • Ib) Job/Parts to remove Q’ty 1st 48 Nm (4.8 m • kg, 35 ft • lb) 2nd 13 Nm (1.3 m • kg, 9.4 ft • lb) Remarks Front cowling assembly Refer to “GENERAL CHASSIS” on page 4-1. Front fork legs Refer to “FRONT FORK” on page 4-44.
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STEERING HEAD YamahaR125.COM Removing the lower bracket T. R. 110 Nm (11.0 m • kg, 80 ft • lb) 2 3 14 12 4 5 LS 15 LS 6 7 9 New 16 8 T. R. 10 11 13 11 Nm (1.1 m • kg, 8.0 ft • Ib) 1 R. R. Order T. T. 7 Nm (0.7 m • kg, 5.1 ft • Ib) Job/Parts to remove Q’ty 13 Upper bearing outer race 1 14 Lower bearing outer race 1 15 Lower bearing inner race 1 16 Dust seal 1 1st 48 Nm (4.8 m • kg, 35 ft • lb) 2nd 13 Nm (1.3 m • kg, 9.
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STEERING HEAD YamahaR125.COM b. Remove the bearing race from the lower bracket with a floor chisel “2” and hammer. c. Install a new dust seal and new bearing races. EAS23110 REMOVING THE LOWER BRACKET 1. Stand the vehicle on a level surface. EWA13120 WARNING ECA5D71039 Securely support the vehicle so that there is no danger of it falling over. 2.
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YamahaR125.COM • Upper ring nut • Lock washer Refer to “CHECKING AND ADJUSTING THE STEERING HEAD” on page 3-22. 3. Install: • Upper bracket • Steering stem nut NOTE: Temporarily tighten the steering stem nut. 4. Install: • Front fork legs Refer to “FRONT FORK” on page 4-44. NOTE: Temporarily tighten the upper and lower bracket pinch bolts. 5. Tighten: • Steering stem nut T. R. Steering stem nut 110 Nm (11.
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REAR SHOCK ABSORBER ASSEMBLY YamahaR125.COM EAS23160 REAR SHOCK ABSORBER ASSEMBLY Removing the rear shock absorber assembly T. R. 44 Nm (4.4 m • kg, 32 ft • Ib) 5 5 7 6 7 4 2 LS LS 8 10 New 9 11 10 New 2 New 10 3 1 LS 11 T. R. LS 3 1 Order 4 11 New 10 Job/Parts to remove 9 44 Nm (4.4 m • kg, 32 ft • Ib) 10 New LS Q’ty Remarks Bottom cowling Refer to “GENERAL CHASSIS” on page 4-1. Rear wheel Refer to “REAR WHEEL” on page 4-12.
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REAR SHOCK ABSORBER ASSEMBLY YamahaR125.COM EAS23230 REMOVING THE REAR SHOCK ABSORBER ASSEMBLY 1. Stand the vehicle on a level surface. Recommended lubricant Lithium-soap-based grease 2. Install: • Bearing “1” (to the relay arm) • Oil seal “2” (to the relay arm) EWA13120 WARNING Securely support the vehicle so that there is no danger of it falling over. NOTE: Place the vehicle on a suitable stand so that the rear wheel is elevated. Oil seal installed depth “a” 0.5 mm (0.
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REAR SHOCK ABSORBER ASSEMBLY YamahaR125.COM 1 FWD 2. Tighten: • Rear shock absorber assembly upper nut T. R. Rear shock absorber assembly upper nut 44 Nm (4.4 m·kg, 32 ft·lb) • Relay arm nut T. R. Relay arm nut 44 Nm (4.4 m·kg, 32 ft·lb) • Rear shock absorber assembly lower nut T. R. Rear shock absorber assembly lower nut 44 Nm (4.4 m·kg, 32 ft·lb) 3. Install: • Connecting arms NOTE: When installing the connecting arms, lift up the swingarm. 4. Tighten: • Connecting arm nuts T. R.
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SWINGARM YamahaR125.COM EAS23330 SWINGARM Removing the swingarm 7 Nm (0.7 m • kg, 5.1 ft • Ib) R. R. R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) T. T. T. 81Nm (8.1 m • kg, 59 ft • Ib) 3 4 2 5 LS 13 14 7 10 New 9 12 LS 13 14 12 T. 11 10 New R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) LS 8 1 6 T. R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) Order 1 Job/Parts to remove Q’ty Muffler Remarks Refer to “ENGINE REMOVAL” on page 5-1. Rear wheel Refer to “REAR WHEEL” on page 4-12.
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SWINGARM YamahaR125.COM Removing the swingarm 7 Nm (0.7 m • kg, 5.1 ft • Ib) R. R. R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) T. T. T. 81Nm (8.1 m • kg, 59 ft • Ib) 3 4 2 5 LS 13 14 7 10 New 9 12 LS 13 14 12 T. 11 10 New R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) LS 8 1 6 T. R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) Order 12 1 Job/Parts to remove Q’ty Dust cover 2 13 Spacer 2 14 Bearing 2 Remarks For installation, reverse the removal procedure.
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SWINGARM YamahaR125.COM EAS23350 REMOVING THE SWINGARM 1. Stand the vehicle on a level surface. 3 1 EWA13120 2 WARNING Securely support the vehicle so that there is no danger of it falling over. NOTE: Place the vehicle on a suitable stand so that the rear wheel is elevated. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 2. Measure: • Swingarm side play • Swingarm vertical movement EAS23360 CHECKING THE SWINGARM 1. Check: • Swingarm Bends/cracks/damage → Replace. 2.
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SWINGARM YamahaR125.COM • Bearings Damage/pitting → Replace. NOTE: Temporarily tighten the pivot shaft nut. c. Turn the swingarm adjusting collar out to tighten it and so that it contacts the dust cover on the swingarm. d. Tighten the pivot shaft nut. EAS23380 T. INSTALLING THE SWINGARM 1. Lubricate: • Bearings • Spacers • Dust covers • Pivot shaft R. Pivot shaft nut 81 Nm (8.1 m·kg, 59 ft·lb) Recommended lubricant Lithium-soap-based grease 2.
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CHAIN DRIVE YamahaR125.COM EAS23400 CHAIN DRIVE Removing the drive chain 5 4 New 2 New 8 7 3 6 T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) T. R. Order 4 New Job/Parts to remove Q’ty 10 Nm (1.0 m • kg, 7.2 ft • Ib) Remarks Bottom cowling Refer to “GENERAL CHASSIS” on page 4-1. Rear wheel Refer to “REAR WHEEL” on page 4-12.
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CHAIN DRIVE YamahaR125.COM EAS23420 REMOVING THE DRIVE CHAIN 1. Stand the vehicle on a level surface. EWA13120 WARNING Securely support the vehicle so that there is no danger of it falling over. NOTE: Place the vehicle on a suitable stand so that the rear wheel is elevated. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 2. Clean: • Drive chain EAS23441 CHECKING THE DRIVE CHAIN 1. Measure: • 15-link section “a” of the drive chain Out of specification → Replace the drive chain. ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a.
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CHAIN DRIVE YamahaR125.COM b. Correct 1. Drive chain roller 2. Drive chain sprocket ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 3. Check: • O-rings “1” Damage → Replace the drive chain. • Drive chain rollers “2” Damage/wear → Replace the drive chain. • Drive chain side plates “3” Damage/wear → Replace the drive chain. Cracks → Replace the drive chain. EAS23470 CHECKING THE REAR WHEEL SPROCKET Refer to “CHECKING AND REPLACING THE REAR WHEEL SPROCKET” on page 4-15.
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YamahaR125.COM NOTE: Install the master link plate with its manufacturer mark facing outward. 4. Install: • Drive sprocket cover NOTE: Be sure not to pinch the neutral switch lead when installing the drive sprocket cover. 5. Install: • Rear wheel Refer to “REAR WHEEL” on page 4-12. 6. Adjust: • Drive chain slack Refer to “ADJUSTING THE DRIVE CHAIN SLACK” on page 3-21. Drive chain slack 30.0–40.0 mm (1.18–1.
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YamahaR125.COM ENGINE ENGINE REMOVAL ........................................................................................ 5-1 INSTALLING THE ENGINE....................................................................... 5-5 INSTALLING THE SHIFT ARM ................................................................. 5-5 INSTALLING THE EXHAUST ASSEMBLY ............................................... 5-5 CYLINDER HEAD............................................................................................
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YamahaR125.COM CLUTCH ........................................................................................................ 5-38 REMOVING THE CLUTCH ..................................................................... 5-42 CHECKING THE FRICTION PLATES..................................................... 5-42 CHECKING THE CLUTCH PLATES ....................................................... 5-42 CHECKING THE CLUTCH SPRINGS.....................................................
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YamahaR125.COM TRANSMISSION............................................................................................ 5-64 CHECKING THE SHIFT FORKS............................................................. 5-67 CHECKING THE SHIFT DRUM ASSEMBLY.......................................... 5-67 CHECKING THE TRANSMISSION ......................................................... 5-67 CHECKING THE CLUTCH PUSH RODS ............................................... 5-68 ASSEMBLING THE MAIN AXLE AND DRIVE AXLE ....
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ENGINE REMOVAL YamahaR125.COM EAS23710 ENGINE REMOVAL Removing the exhaust assembly T. R. 20 Nm (2.0 m • kg, 14 ft • Ib) 4 New 6 2 2 3 1 5 T. R. Order Job/Parts to remove 20 Nm (2.0 m • kg, 14 ft • Ib) Q’ty Remarks Refer to “GENERAL CHASSIS” on page 4-1.
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ENGINE REMOVAL YamahaR125.COM Disconnecting the leads and couplers 1 6 4 4 3 7 8 2 5 9 T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) T. R. Order Job/Parts to remove 10 Nm (1.0 m • kg, 7.2 ft • Ib) Q’ty Remarks ECA5D71020 CAUTION: First, disconnect the negative battery lead, then the positive battery lead. Negative battery lead/Positive battery lead Refer to “CHECKING AND CHARGING THE BATTERY” on page 3-27. Seat/Bottom cowlings/Air filter case Refer to “GENERAL CHASSIS” on page 4-1.
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ENGINE REMOVAL YamahaR125.COM Disconnecting the leads and couplers 1 6 4 4 3 7 8 2 5 9 T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) T. R. Order Job/Parts to remove 10 Nm (1.0 m • kg, 7.2 ft • Ib) Q’ty Remarks Air induction system reed valve assembly Refer to “AIR INDUCTION SYSTEM” on page 7-9. Drive sprocket cover/Drive sprocket Refer to “CHAIN DRIVE” on page 4-63. 1 Spark plug cap 1 Disconnect. 2 Sidestand switch lead 1 Disconnect.
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ENGINE REMOVAL YamahaR125.COM Removing the engine T. R. 46 Nm (4.6 m • kg, 33 ft • Ib) 1 1 3 4 2 3 2 T. R. Order Job/Parts to remove 46 Nm (4.6 m • kg, 33 ft • Ib) Q’ty Remarks NOTE: Place a suitable stand under the engine. 1 Engine mounting bolt/nut (front side) 1/1 2 Engine mounting bolt/nut (rear lower side) 1/1 3 Engine mounting bolt/nut (rear upper side) 1/1 4 Engine 1 For installation, reverse the removal procedure.
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ENGINE REMOVAL YamahaR125.COM EAS23720 EAS5D71030 INSTALLING THE ENGINE 1. Install: • Engine “1” • Engine mounting bolt (rear lower side) “2” • Engine mounting nut (rear lower side) “3” • Engine mounting bolt (rear upper side) “4” • Engine mounting nut (rear upper side) “5” • Engine mounting bolt (front side) “6” • Engine mounting nut (front side) “7” INSTALLING THE SHIFT ARM 1.
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CYLINDER HEAD YamahaR125.COM EAS24100 CYLINDER HEAD Removing the cylinder head T. R. T. 22 Nm (2.2 m • kg, 16 ft • Ib) R. T. 1 R. 13 Nm (1.3 m • kg, 9.4 ft • Ib) ∗ T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) 8 46 Nm (4.6 m • kg, 33 ft • Ib) T. R. (4) T. New R. 2 10 Nm (1.0 m • kg, 7.2 ft • Ib) 10 Nm (1.0 m • kg, 7.2 ft • Ib) 9 New 10 E 5 6 5 New 7 (4) 13 LS E (4) E M New New 12 4 11 New 14 15 E T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) T. R. 15 R. Order 16 T. 7 Nm (0.
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CYLINDER HEAD YamahaR125.COM Removing the cylinder head T. R. T. 22 Nm (2.2 m • kg, 16 ft • Ib) R. T. 1 R. 13 Nm (1.3 m • kg, 9.4 ft • Ib) ∗ T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) T. R. (4) T. New R. 2 10 Nm (1.0 m • kg, 7.2 ft • Ib) 8 46 Nm (4.6 m • kg, 33 ft • Ib) 10 Nm (1.0 m • kg, 7.2 ft • Ib) 9 New 10 E 5 6 5 New 7 (4) 13 LS E (4) E M New New 12 4 11 New 14 15 E T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) T. R. 15 R. Order 16 T. 7 Nm (0.7 m • kg, 5.
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CYLINDER HEAD YamahaR125.COM EAS24130 NOTE: REMOVING THE CYLINDER HEAD 1. Align: • “I” mark “a” on the generator rotor (with the stationary pointer “b” on the generator cover) To prevent the timing chain from falling into the crankcase, fasten it with a wire “1”. ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Turn the crankshaft counterclockwise. b. When the piston is at TDC on the compression stroke, align the “I” mark “c” on the camshaft sprocket with the mark “d” on the cylinder head. 1 b 4.
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CYLINDER HEAD YamahaR125.COM EAS5D71031 CHECKING THE CAMSHAFT SPROCKET AND TIMING CHAIN GUIDE 1. Check: • Camshaft sprocket More than 1/4 tooth wear “a” → Replace the camshaft sprocket, timing chain and crankshaft as a set. 2. Check: • Cylinder head Damage/scratches → Replace. • Cylinder head water jacket Mineral deposits/rust → Eliminate. 3. Measure: • Cylinder head warpage Out of specification → Resurface the cylinder head. a. b. 1. 2. Warpage limit 0.03 mm (0.
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CYLINDER HEAD YamahaR125.COM c. Make sure that the timing chain tensioner rod comes out of the timing chain tensioner housing smoothly. If there is rough movement, replace the timing chain tensioner. A 2 2 B ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ EAS5D71009 CHECKING THE DECOMPRESSION SYSTEM 1. Check: • Decompression system ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ EAS24230 INSTALLING THE CYLINDER HEAD 1.
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CYLINDER HEAD YamahaR125.COM e. While holding the camshaft, temporarily tighten the camshaft sprocket bolt. f. Remove the wire from the timing chain. 2 1 3 5 ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 4. Install: 1 • Timing chain tensioner gasket New • Timing chain tensioner 6 4 2 ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Apply sealant to the timing chain tensioner bolt threads. 2 3. Install: • Camshaft sprocket Yamaha bond No. 1215 90890-85505 (Three Bond No.1215®) ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a.
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YamahaR125.COM 5. Turn: • Crankshaft (several turns counterclockwise) 6. Check: • “I” mark “a” Align the “I” mark on the generator rotor with the stationary pointer “b” on the generator cover. • “I” mark “c” Align the “I” mark on the camshaft sprocket with the stationary pointer “d” on the cylinder head. Out of alignment → Correct. Refer to the installation steps above. b a d c 7. Tighten: • Camshaft sprocket bolt T. R. Camshaft sprocket bolt 30 Nm (3.
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CAMSHAFT YamahaR125.COM EAS23730 CAMSHAFT Removing the rocker arms and camshaft T. R. 1 7 Nm (0.7 m • kg, 5.1 ft • Ib) 1 2 2 5 M M 2 1 4 1 2 6 E 7 M E 4 T. R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) E New M 3 M T. R. Order Job/Parts to remove Q’ty Cylinder head 7 Nm (0.7 m • kg, 5.1 ft • Ib) Remarks Refer to “CYLINDER HEAD” on page 5-7.
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CAMSHAFT YamahaR125.COM EAS23840 CHECKING THE CAMSHAFT 1. Check: • Camshaft lobes Blue discoloration/pitting/scratches → Replace the camshaft. 2. Measure: • Camshaft lobe dimensions “a” and “b” Out of specification → Replace the camshaft. Camshaft lobe dimensions Intake A 30.225–30.325 mm (1.1900– 1.1939 in) Limit 30.125 mm (1.1860 in) Intake B 25.127–25.227 mm (0.9893– 0.9932 in) Limit 25.027 mm (0.9853 in) Exhaust A 30.232–30.332 mm (1.1902– 1.1942 in) Limit 30.132 mm (1.1863 in) Exhaust B 25.065–25.
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CAMSHAFT YamahaR125.COM 5. Calculate: • Rocker-arm-to-rocker-arm-shaft clearance 4. Install: • Rocker arms • Rocker arm shafts “1” NOTE: Calculate the clearance by subtracting the rocker arm shaft outside diameter from the rocker arm inside diameter. NOTE: • Make sure that the cutout “a” in each rocker arm shaft is facing downward as shown in the illustration. • Make sure the rocker arm shafts (intake and exhaust) are completely pushed into the cylinder head.
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YamahaR125.COM VALVES AND VALVE SPRINGS EAS24270 VALVES AND VALVE SPRINGS Removing the valves and valve springs 1 2 1 3 6 New 2 3 7 New 6 M 8 7 M M 8 5 M 2 1 7 6 New 3 8 5 1 2 6 New 3 7 8 M M 4 4 M Order Job/Parts to remove Q’ty Cylinder head Remarks Refer to “CYLINDER HEAD” on page 5-7. Rocker arms/Camshaft Refer to “CAMSHAFT” on page 5-14.
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YamahaR125.COM VALVES AND VALVE SPRINGS EAS24280 REMOVING THE VALVES The following procedure applies to all of the valves and related components. 2 NOTE: Before removing the internal parts of the cylinder head (e.g., valves, valve springs, valve seats), make sure the valves properly seal. 1 1. Check: • Valve sealing Leakage at the valve seat → Check the valve face, valve seat, and valve seat width. Refer to “CHECKING THE VALVE SEATS” on page 5-20. 3.
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YamahaR125.COM VALVES AND VALVE SPRINGS b. Install the new valve guide with the valve guide installer “2” and valve guide remover “1”. Valve-stem-to-valve-guide clearance (intake) 0.010–0.037 mm (0.0004–0.0015 in) Limit 0.080 mm (0.0032 in) Valve-stem-to-valve-guide clearance (exhaust) 0.025–0.052 mm (0.0010–0.0020 in) Limit 0.100 mm (0.0039 in) Valve guide position (intake) 17.0–17.4 mm (0.669–0.685 in) Valve guide position (exhaust) 14.0–14.4 mm (0.551–0.567 in) a. Valve guide position c.
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YamahaR125.COM VALVES AND VALVE SPRINGS 3. Eliminate: • Carbon deposits (from the valve face and valve seat) 4. Check: • Valve face Pitting/wear → Grind the valve face. • Valve stem end Mushroom shape or diameter larger than the body of the valve stem → Replace the valve. 5. Measure: • Valve margin thickness D “a” Out of specification → Replace the valve. EAS24300 CHECKING THE VALVE SEATS The following procedure applies to all of the valves and valve seats. 1.
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YamahaR125.COM VALVES AND VALVE SPRINGS 4. Lap: • Valve face • Valve seat NOTE: After replacing the cylinder head or replacing the valve and valve guide, the valve seat and valve face should be lapped. ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Apply a coarse lapping compound “a” to the valve face. e. Apply a fine lapping compound to the valve face and repeat the above steps. f. After every lapping procedure, be sure to clean off all of the lapping compound from the valve face and valve seat. g.
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YamahaR125.COM VALVES AND VALVE SPRINGS Free length (intake) 41.71 mm (1.64 in) Limit 39.62 mm (1.56 in) Free length (exhaust) 41.71 mm (1.64 in) Limit 39.62 mm (1.56 in) Spring tilt (intake) 2.5°/1.8 mm Spring tilt (exhaust) 2.5°/1.8 mm EAS24340 INSTALLING THE VALVES The following procedure applies to all of the valves and related components. 1. Deburr: • Valve stem end (with an oil stone) 2. Measure: • Compressed valve spring force “a” Out of specification → Replace the valve spring.
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YamahaR125.COM VALVES AND VALVE SPRINGS • Valve “3” • Valve spring “4” • Upper spring seat “5” (into the cylinder head) 2 NOTE: • Make sure each valve is installed in its original place. • Install the valve springs with the larger pitch “a” facing up. 1 5. To secure the valve cotters onto the valve stem, lightly tap the valve tip with a soft-face hammer. ECA13800 CAUTION: Hitting the valve tip with excessive force could damage the valve. b. Smaller pitch 4.
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CYLINDER AND PISTON YamahaR125.COM EAS24350 CYLINDER AND PISTON Removing the cylinder and piston 7 E 8 9 E 6 5 1 E New 4 4 New New E 2 New 3 T. R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) 3 Order Job/Parts to remove Q’ty Cylinder head Remarks Refer to “CYLINDER HEAD” on page 5-7. 1 Cylinder 1 2 Cylinder gasket 1 3 Dowel pin 2 4 Piston pin clip 2 5 Piston pin 1 6 Piston 1 7 Top ring 1 8 2nd ring 1 9 Oil ring 1 For installation, reverse the removal procedure.
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CYLINDER AND PISTON YamahaR125.COM EAS24380 REMOVING THE PISTON 1. Remove: • Piston pin clips “1” • Piston pin “2” • Piston “3” NOTE: When removing a piston ring, open the end gap with your fingers and lift the other side of the ring over the piston crown. ECA13810 CAUTION: Do not use a hammer to drive the piston pin out. NOTE: • Before removing the piston pin clip, cover the crankcase opening with a clean rag to prevent the piston pin clip from falling into the crankcase.
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CYLINDER AND PISTON YamahaR125.COM EAS24430 “C” = maximum of D1–D2 CHECKING THE PISTON RINGS 1. Measure: • Piston ring side clearance Out of specification → Replace the piston and piston rings as a set. “T” = maximum of D1 or D2 - maximum of D5 or D6 “R” = maximum of D1, D3 or D5 - minimum of D2, D4 or D6 NOTE: Before measuring the piston ring side clearance, eliminate any carbon deposits from the piston ring grooves and piston rings. b.
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CYLINDER AND PISTON YamahaR125.COM 3. Measure: • Piston pin bore diameter “b” Out of specification → Replace the piston. 3. Measure: • Piston ring end gap Out of specification → Replace the piston ring. Piston pin bore inside diameter 14.002–14.013 mm (0.5513– 0.5517 in) Limit 14.043 mm (0.5529 in) NOTE: The oil ring expander spacer end gap cannot be measured. If the oil ring rail gap is excessive, replace all three piston rings. Piston ring Top ring End gap (installed) 0.10–0.25 mm (0.0039–0.
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CYLINDER AND PISTON YamahaR125.COM 120 e a 120 120 f d f c b A 2. Install: • Piston “1” • Piston pin “2” a. b. c. d. e. f. A. • Piston pin clips “3” New NOTE: • Apply engine oil to the piston pin. • Make sure the arrow mark “a” on the piston points towards the exhaust side of the cylinder. • Before installing the piston pin clips, cover the crankcase opening with a clean rag to prevent the clips from falling into the crankcase.
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GENERATOR AND STARTER CLUTCH YamahaR125.COM EAS5D71010 GENERATOR AND STARTER CLUTCH Removing the generator and starter clutch 2 10 Nm (1.0 m • kg, 7.2 ft • Ib) T. 1 R. 8 T. R. New 7 10 Nm (1.0 m • kg, 7.2 ft • Ib) LT 12 9 3 (3) 8 17 19 14 16 LS 15 10 E E 4 13 E New 18 6 New (3) E T. R. 14 Nm (1.4 m • kg, 10 ft • Ib) (7) 5 E 20 11 Job/Parts to remove R. R. 70 Nm (7.0 m • kg, 50 ft • lb) T. T. Order LS Q’ty 10 Nm (1.0 m • kg, 7.
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GENERATOR AND STARTER CLUTCH YamahaR125.COM Removing the generator and starter clutch 2 10 Nm (1.0 m • kg, 7.2 ft • Ib) T. 1 R. 8 T. R. New 7 10 Nm (1.0 m • kg, 7.2 ft • Ib) LT 12 9 3 (3) 8 17 19 14 16 LS 15 10 E E 4 13 E New 18 6 New (3) E T. R. 14 Nm (1.4 m • kg, 10 ft • Ib) (7) 5 E 11 70 Nm (7.0 m • kg, 50 ft • lb) Job/Parts to remove Q’ty Woodruff key R. R. 12 20 T. T. Order LS 10 Nm (1.0 m • kg, 7.
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GENERATOR AND STARTER CLUTCH YamahaR125.COM EAS24490 REMOVING THE GENERATOR 1. Remove: • Generator rotor nut “1” • Washer 1 2 NOTE: • While holding the generator rotor “2” with the sheave holder “3”, loosen the generator rotor nut. • Do not allow the sheave holder to touch the projection on the generator rotor. Sheave holder 90890-01701 Primary clutch holder YS-01880-A EAS24560 REMOVING THE STARTER CLUTCH 1.
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GENERATOR AND STARTER CLUTCH YamahaR125.COM 1 2 NOTE: 3 • While holding the generator rotor “2” with the sheave holder “3”, tighten the starter clutch bolts. • Do not allow the sheave holder to touch the projection on the generator rotor. • Stake the end “a” of each starter clutch bolt. 1 2 3 2 3 1 Sheave holder 90890-01701 Primary clutch holder YS-01880-A 2. Check: • Starter clutch idle gear • Starter clutch gear Burrs/chips/roughness/wear → Replace the defective part(s). 3.
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GENERATOR AND STARTER CLUTCH YamahaR125.COM NOTE: 1,6 • While holding the generator rotor “2” with the sheave holder “3”, tighten the generator rotor nut. • Do not allow the sheave holder to touch the projection on the generator rotor. 7 8 5 4 Sheave holder 90890-01701 Primary clutch holder YS-01880-A 9 3,11 1 3 2 3. Apply: • Sealant (onto the crankshaft position sensor/stator assembly lead grommet) Yamaha bond No. 1215 90890-85505 (Three Bond No.1215®) 4. Install: • Generator cover T. R.
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ELECTRIC STARTER YamahaR125.COM EAS24780 ELECTRIC STARTER Removing the starter motor T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) 2 1 Order Job/Parts to remove Q’ty Remarks Refer to “GENERAL CHASSIS” on page 4-1. Lower side cowlings 1 Starter motor 1 2 Starter motor lead 1 Disconnect. For installation, reverse the removal procedure.
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ELECTRIC STARTER YamahaR125.COM Disassembling the starter motor 1 New LS 5 6 7 3 New 4 2 7 6 Order 1 Job/Parts to remove Q’ty O-ring Remarks 1 2 Starter motor yoke 1 3 O-ring 1 4 Commutator 1 5 Starter motor front cover/brush holder set 1 6 Brush 2 7 Brush spring 2 For assembly, reverse the disassembly procedure.
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YamahaR125.COM ELECTRIC STARTER EAS24790 CHECKING THE STARTER MOTOR 1. Check: • Commutator Dirt → Clean with 600 grit sandpaper. 2. Measure: • Commutator diameter “a” Out of specification → Replace the starter motor. Pocket tester 90890-03112 Analog pocket tester YU-03112-C Armature coil Commutator resistance “1” 0.0315–0.0385 Ω Insulation resistance “2” Above 1 MΩ Limit 16.6 mm (0.65 in) b. If any resistance is out of specification, replace the starter motor. a 3.
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YamahaR125.COM 7. Check: • Gear teeth Damage/wear → Replace the gear. 8. Check: • Bearing • Oil seal Damage/wear → Replace the starter motor front cover/brush holder set. EAS24800 ASSEMBLING THE STARTER MOTOR 1. Install: • Starter motor front cover/brush holder set “1” • Starter motor yoke “2” NOTE: Align the marks “a” on the starter motor yoke and starter motor front cover/brush holder set.
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CLUTCH YamahaR125.COM EAS25061 CLUTCH Removing the clutch cover T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) 1 6 New 5 7 New E 6 3 4 New 2 LS (4) (6) T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) Job/Parts to remove R. T. Order LS 10 Nm (1.0 m • kg, 7.2 ft • Ib) Q’ty Remarks Engine oil Drain. Refer to “CHANGING THE ENGINE OIL” on page 3-11. Right lower side cowling Refer to “GENERAL CHASSIS” on page 4-1.
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CLUTCH YamahaR125.COM Removing the clutch T. R. 70 Nm (7.0 m • kg, 50 ft • lb) 14 New T. R. 12 Nm (1.2 m • kg, 8.7 ft • Ib) T. R. 8 Nm (0.8 m • kg, 5.
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CLUTCH YamahaR125.COM Removing the clutch T. R. 70 Nm (7.0 m • kg, 50 ft • lb) 14 New T. R. 12 Nm (1.2 m • kg, 8.7 ft • Ib) T. R. 8 Nm (0.8 m • kg, 5.8 ft • Ib) E 13 3 6 15 4 5 1 12 11 10 18 8 (4) (4) 8 8 2 8 9 16 9 17 9 7 E E Order 18 Job/Parts to remove Q’ty Conical spring washer Remarks 1 For installation, reverse the removal procedure.
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CLUTCH YamahaR125.COM Removing the push lever 1 E 2 3 New LS E 4 New 5 Order Job/Parts to remove Q’ty 1 Clutch push lever 2 Clutch push lever spring 1 3 Circlip 1 4 Oil seal 1 5 Bearing 1 Remarks 1 For installation, reverse the removal procedure.
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CLUTCH YamahaR125.COM EAS25070 REMOVING THE CLUTCH 1. Straighten the lock washer tab. 2. Loosen: • Clutch boss nut “1” NOTE: While holding the clutch boss “2” with the universal clutch holder “3”, loosen the clutch boss nut. Universal clutch holder 90890-04086 YM-91042 A B 1 2 3 C EAS25100 CHECKING THE FRICTION PLATES The following procedure applies to all of the friction plates. 1. Check: • Friction plate Damage/wear → Replace the friction plates as a set. 2.
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CLUTCH YamahaR125.COM Clutch plate thickness 1.45–1.75 mm (0.057–0.069 in) Warpage limit 0.20 mm (0.0079 in) 2. Check: • Bearing Damage/wear → Replace the bearing and clutch housing. EAS25160 CHECKING THE CLUTCH BOSS 1. Check: • Clutch boss splines Damage/pitting/wear → Replace the clutch boss. EAS25140 CHECKING THE CLUTCH SPRINGS The following procedure applies to all of the clutch springs. 1. Check: • Clutch spring Damage → Replace the clutch springs as a set. 2.
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CLUTCH YamahaR125.COM 2. Check: • Primary drive gear Damage/wear → Replace the primary drive gear and clutch housing as a set. Excessive noise during operation → Replace the primary drive gear and clutch housing as a set. 3. Install: • Primary drive gear Refer to “BALANCER GEAR” on page 5-53. NOTE: Be sure to install the thrust washer so that its sharp edge “a” is facing away from the clutch boss. 1 a EAS25210 CHECKING THE PRIMARY DRIVEN GEAR 1.
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CLUTCH YamahaR125.COM NOTE: Tighten the clutch spring bolts in stages and in a crisscross pattern. 2 1 3 1 5. Bend the lock washer tab along a flat side of the nut. 6. Lubricate: • Friction plates • Clutch plates (with the recommended lubricant) 9. Adjust: • Clutch mechanism free play ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a.
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YamahaR125.COM 2 3 ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 10.Install: • Oil seal “1” Installed depth of oil seal “a” 1.4–1.9 mm (0.055–0.075 in) 1 a 11.Install: • Clutch cover T. Clutch cover bolt 10 Nm (1.0 m·kg, 7.2 ft·lb) R. NOTE: Tighten the clutch cover bolts in the proper tightening sequence as shown. 6 1,7 8 9 5 4 10 2,12 3,13 11 12.Adjust: • Clutch cable free play Refer to “ADJUSTING THE CLUTCH CABLE FREE PLAY” on page 3-12.
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OIL PUMP YamahaR125.COM EAS24911 OIL PUMP Removing the oil pump 3 T. R. 4 Nm (0.4 m • kg, 2.9 ft • Ib) 2 1 LT LT T. R. Order Job/Parts to remove Q’ty Clutch housing 10 Nm (1.0 m • kg, 7.2 ft • Ib) Remarks Refer to “CLUTCH” on page 5-38. Balancer drive gear Refer to “BALANCER GEAR” on page 5-53. 1 Oil baffle plate 1 2 Oil pump assembly 1 3 Oil pump drive gear 1 For installation, reverse the removal procedure.
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OIL PUMP YamahaR125.COM Disassembling the oil pump 2 6 5 4 3 E 1 Order E Job/Parts to remove Q’ty 1 Oil pump housing cover 2 Pin 1 3 Oil pump driven gear 1 4 Oil pump inner rotor 1 5 Oil pump outer rotor 1 6 Oil pump housing 1 Remarks 1 For assembly, reverse the disassembly procedure.
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OIL PUMP YamahaR125.COM EAS24960 CHECKING THE OIL PUMP 1. Check: • Oil pump drive gear • Oil pump driven gear • Oil pump housing • Oil pump housing cover Cracks/damage/wear → Replace the defective part(s). 2. Measure: • Inner-rotor-to-outer-rotor-tip clearance “a” • Outer-rotor-to-oil-pump-housing clearance “b” • Oil-pump-housing-to-inner-rotor-and-outerrotor clearance “c” Out of specification → Replace the oil pump. Inner-rotor-to-outer-rotor-tip clearance Less than 0.15 mm (0.0059 in) Limit 0.23 mm (0.
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YamahaR125.COM 1 2 a 3. Check: • Oil pump operation Refer to “CHECKING THE OIL PUMP” on page 5-49. EAS25020 INSTALLING THE OIL PUMP 1. Install: • Oil pump assembly T. R. Oil pump assembly screw 4 Nm (0.4 m·kg, 2.9 ft·lb) ECA5D71021 CAUTION: After tightening the screws, make sure the oil pump turns smoothly.
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SHIFT SHAFT YamahaR125.COM EAS25410 SHIFT SHAFT Removing the shift shaft and stopper lever 6 LS New 2 3 E LT 4 5 1 T. R. Order 10 Nm (1.0 m • kg, 7.2 ft • Ib) Job/Parts to remove Q’ty Clutch housing Remarks Refer to “CLUTCH” on page 5-38. Shift arm Refer to “ENGINE REMOVAL” on page 5-1. 1 Shift shaft 1 2 Circlip 1 3 Shift shaft spring 1 4 Stopper lever 1 5 Stopper lever spring 1 6 Oil seal 1 For installation, reverse the removal procedure.
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SHIFT SHAFT YamahaR125.COM EAS25420 CHECKING THE SHIFT SHAFT 1. Check: • Shift shaft Bends/damage/wear → Replace. • Shift shaft spring Damage/wear → Replace. EAS25430 CHECKING THE STOPPER LEVER 1. Check: • Stopper lever Bends/damage → Replace. Roller turns roughly → Replace the stopper lever. • Stopper lever spring Damage/wear → Replace. 2 EAS25450 INSTALLING THE SHIFT SHAFT 1.
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BALANCER GEAR YamahaR125.COM EAS5D71017 BALANCER GEAR Removing the primary drive gear and balancer gears 6 5 4 10 9 3 1 8 T. R. 60 Nm (6.0 m • kg, 43 ft • Ib) 7 New 2 T. R. Order 50 Nm (5.0 m • kg, 36 ft • Ib) Job/Parts to remove Q’ty Clutch housing Remarks Refer to “CLUTCH” on page 5-38.
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BALANCER GEAR YamahaR125.COM EAS5D71018 EAS5D71021 REMOVING THE PRIMARY DRIVE GEAR AND BALANCER GEARS 1. Loosen: • Primary drive gear nut “1” INSTALLING THE PRIMARY DRIVE GEAR AND BALANCER GEARS 1.
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YamahaR125.COM • Place the aluminum plate “b” between the balancer drive gear “3” and the balancer driven gear “4”, and then tighten the primary drive gear nut. 3 4 1 a 3 b 2 4 3. Bend the lock washer tab along a flat side of the nut.
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CRANKCASE YamahaR125.COM EAS25540 CRANKCASE Separating the crankcase T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) 8 10 T. 9 R. 8 10 Nm (1.0 m • kg, 7.2 ft • Ib) 12 11 2 6 3 1 5 New 11 7 LS 4 New T. R. 32 Nm (3.2 m • kg, 23 ft • Ib) T. R. T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) 20 Nm (2.0 m • kg, 14 ft • Ib) T. R. Order Job/Parts to remove Q’ty Engine 10 Nm (1.0 m • kg, 7.2 ft • Ib) Remarks Refer to “ENGINE REMOVAL” on page 5-1. Cylinder head Refer to “CYLINDER HEAD” on page 5-7.
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CRANKCASE YamahaR125.COM Separating the crankcase T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) 8 10 T. 9 R. 8 10 Nm (1.0 m • kg, 7.2 ft • Ib) 12 11 2 6 3 1 5 New 11 7 LS 4 New T. R. 32 Nm (3.2 m • kg, 23 ft • Ib) T. R. T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) 20 Nm (2.0 m • kg, 14 ft • Ib) T. R. Order Job/Parts to remove Q’ty 6 Engine oil strainer 7 Neutral switch 1 8 Circlip 2 9 Spacer 1 10 Right crankcase 1 11 Dowel pin 2 12 Left crankcase 1 10 Nm (1.0 m • kg, 7.
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CRANKCASE YamahaR125.COM Removing the oil seal and bearings 3 E T. R. 7 Nm (0.7 m • kg, 5.1 ft • Ib) 3 E 2 3 3 3 3 LT 1 3 LS E Order Job/Parts to remove Q’ty Crankshaft/Balancer Remarks Refer to “CRANKSHAFT” on page 5-61. Transmission Refer to “TRANSMISSION” on page 5-64. 1 Oil seal 1 2 Bearing retainer 1 3 Bearing 7 For installation, reverse the removal procedure.
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CRANKCASE YamahaR125.COM EAS5D71032 ECA13900 SEPARATING THE CRANKCASE 1. Remove: • Crankcase bolts CAUTION: Tap on one side of the crankcase with a softface hammer. Tap only on reinforced portions of the crankcase, not on the crankcase mating surfaces. Work slowly and carefully and make sure the crankcase halves separate evenly. NOTE: Loosen each bolt 1/4 of a turn at a time, in stages and in the proper sequence as shown. A 2 EAS25580 CHECKING THE CRANKCASE 1.
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CRANKCASE YamahaR125.COM • Oil seal Damage/wear → Replace. 3. Install: • Right crankcase NOTE: EAS5D71015 INSTALLING THE BEARING RETAINER 1. Install: • Bearing retainer “1” Turn the shift drum segment “1” to the position shown in the illustration. In this position, the shift drum segment teeth will not contact the crankcase during crankcase installation. NOTE: • Install the bearing retainer “1” with its “OUT” mark “a” facing outward.
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CRANKSHAFT YamahaR125.COM EAS25960 CRANKSHAFT Removing the crankshaft and balancer 2 E E LS 1 LS New New Order Job/Parts to remove Q’ty Remarks Separate. Refer to “CRANKCASE” on page 5-56. Crankcase 1 Balancer 1 2 Crankshaft 1 For installation, reverse the removal procedure.
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CRANKSHAFT YamahaR125.COM EAS5D71016 REMOVING THE CRANKSHAFT 1. Remove: • Crankshaft “1” NOTE: • Remove the crankshaft with the crankcase separating tool “2”. • Make sure the crankcase separating tool is centered over the crankshaft. ECA5D71022 CAUTION: 2. Measure: • Big end side clearance Out of specification → Replace the crankshaft. • To protect the end of the crankshaft, place an appropriate sized socket between the crankcase separating tool bolt and the crankshaft. • Do not tap on the crankshaft.
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YamahaR125.COM Crankshaft installer pot 90890-01274 Installing pot YU-90058 Crankshaft installer bolt 90890-01275 Bolt YU-90060 Adapter (M12) 90890-01278 Adapter #3 YU-90063 Spacer (crankshaft installer) 90890-04081 Pot spacer YM-91044 1 2 5 4 3 ECA13970 CAUTION: To avoid scratching the crankshaft and to ease the installation procedure, lubricate the oil seal lips with lithium-soap-based grease and each bearing with engine oil.
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TRANSMISSION YamahaR125.COM EAS26241 TRANSMISSION Removing the transmission, shift drum assembly, and shift forks 7 4 8 E 5 9 6 E E E 2 3 1 2 E Order Job/Parts to remove Q’ty Remarks Separate. Refer to “CRANKCASE” on page 5-56.
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TRANSMISSION YamahaR125.COM Disassembling the main axle M 7 M 6 5 M 4 3 2 1 Order Job/Parts to remove Q’ty 1 2nd pinion gear 2 6th pinion gear 1 3 3rd/4th pinion gear 1 4 Circlip 1 5 Toothed washer 1 6 5th pinion gear 1 7 Main axle/1st pinion gear 1 Remarks 1 For assembly, reverse the disassembly procedure.
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TRANSMISSION YamahaR125.COM Disassembling the drive axle 4 5 6 7 8 9 10 11 M 12 M 3 2 1 M M Order 1 Job/Parts to remove Q’ty Washer 1 2 2nd wheel gear 1 3 6th wheel gear 1 4 Washer 1 5 1st wheel gear 1 6 Spacer 1 7 5th wheel gear 1 8 Circlip 1 9 Toothed washer 1 10 4th wheel gear 1 11 3rd wheel gear 1 12 Drive axle 1 Remarks For assembly, reverse the disassembly procedure.
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TRANSMISSION YamahaR125.COM EAS26260 EAS26270 2. Check: • Shift fork guide bar Roll the shift fork guide bar on a flat surface. Bends → Replace. EAS26290 CHECKING THE SHIFT FORKS The following procedure applies to all of the shift forks. 1. Check: • Shift fork cam follower “1” • Shift fork pawl “2” Bends/damage/scoring/wear → Replace the shift fork. CHECKING THE SHIFT DRUM ASSEMBLY 1. Check: • Shift drum groove Damage/scratches/wear → Replace the shift drum assembly.
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TRANSMISSION YamahaR125.COM EAS29020 ASSEMBLING THE MAIN AXLE AND DRIVE AXLE 1. Install: • Toothed washer “1” • Circlip “2” New NOTE: • Be sure to install the circlip so that its sharp edge “a” is facing away from the toothed washer and gear. • Be sure the circlip ends “b” are positioned at the axle spline groove “c”. 3. Check: • Transmission gears Blue discoloration/pitting/wear → Replace the defective gear(s). • Transmission gear dogs Cracks/damage/rounded edges → Replace the defective gear(s).
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YamahaR125.COM NOTE: The embossed marks on the shift forks should face towards the right side of the engine and be in the following sequence: “R”, “C”, “L”. 5 3 2 1 4 2. Check: • Transmission Rough movement → Repair. NOTE: • Apply engine oil to each gear and bearing thoroughly. • Before assembling the crankcase, make sure that the transmission is in neutral and that the gears turn freely.
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YamahaR125.COM COOLING SYSTEM RADIATOR ...................................................................................................... 6-1 CHECKING THE RADIATOR.................................................................... 6-3 INSTALLING THE RADIATOR.................................................................. 6-3 THERMOSTAT ................................................................................................ 6-4 CHECKING THE THERMOSTAT...........................................
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RADIATOR YamahaR125.COM EAS26380 RADIATOR Removing the radiator T. R. 8 11 8 Nm (0.8 m • kg, 5.8 ft • Ib) 6 7 10 4 2 5 1 9 3 T . R. T. R. Order Job/Parts to remove 7 Nm (0.7 m • kg, 5.1 ft • Ib) 10 Nm (1.0 m • kg, 7.2 ft • Ib) Q’ty Remarks Coolant Drain. Refer to “CHANGING THE COOLANT” on page 3-15. Rider seat/Bottom cowling Refer to “GENERAL CHASSIS” on page 4-1. Fuel tank Refer to “FUEL TANK” on page 7-1.
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RADIATOR YamahaR125.COM Removing the radiator T. R. 8 11 8 Nm (0.8 m • kg, 5.8 ft • Ib) 6 7 10 4 2 5 1 9 3 T . R. T. R. Order 11 Job/Parts to remove Q’ty Radiator cover 7 Nm (0.7 m • kg, 5.1 ft • Ib) 10 Nm (1.0 m • kg, 7.2 ft • Ib) Remarks 1 For installation, reverse the removal procedure.
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RADIATOR YamahaR125.COM EAS26390 CHECKING THE RADIATOR 1. Check: • Radiator fins Obstruction → Clean. Apply compressed air to the rear of the radiator. Damage → Repair or replace. NOTE: Straighten any flattened fins with a thin, flat-head screwdriver. b. Apply the specified pressure for ten seconds and make sure there is no drop in pressure. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 4. Check: • Radiator fan Damage → Replace. Malfunction → Check and repair. Refer to “COOLING SYSTEM” on page 8-25.
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THERMOSTAT YamahaR125.COM EAS26440 THERMOSTAT Removing the thermostat 5 1 2 New T. R. 3 18 Nm (1.8 m • kg, 13 ft • Ib) 4 T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) Order Job/Parts to remove Q’ty Remarks Coolant Drain. Refer to “CHANGING THE COOLANT” on page 3-15. Rider seat/Right upper side cowling Refer to “GENERAL CHASSIS” on page 4-1. Fuel tank Refer to “FUEL TANK” on page 7-1.
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THERMOSTAT YamahaR125.COM 2. Check: • Thermostat cover Cracks/damage → Replace. 3. Check: • Radiator inlet hose Cracks/damage → Replace. EAS26450 CHECKING THE THERMOSTAT 1. Check: • Thermostat Does not open at 80.5–83.5 °C (176.9–182.3 °F) → Replace. EAS26480 INSTALLING THE THERMOSTAT 1. Install: • Thermostat NOTE: Install the thermostat with its breather hole “a” facing up. ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Suspend the thermostat “1” in a container “2” filled with water. b.
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WATER PUMP YamahaR125.COM EAS26500 WATER PUMP Removing the water pump 2 1 3 LS New 5 4 New LS T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) T. R. Order Job/Parts to remove 10 Nm (1.0 m • kg, 7.2 ft • Ib) Q’ty Remarks It is not necessary to remove the water pump unless the coolant level is extremely low or the coolant contains engine oil. Coolant Drain. Refer to “CHANGING THE COOLANT” on page 3-15. Left upper side cowling Refer to “GENERAL CHASSIS” on page 4-1.
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WATER PUMP YamahaR125.COM Disassembling the water pump T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) 4 6 7 New 9 LT 8 New 5 T. R. 10 10 Nm (1.0 m • kg, 7.2 ft • Ib) LS 3 New 2 1 Job/Parts to remove R. Order T.
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WATER PUMP YamahaR125.COM EAS26510 ECA14080 DISASSEMBLING THE WATER PUMP 1. Remove: • Water pump seal “1” CAUTION: Never lubricate the water pump seal surface with oil or grease. NOTE: NOTE: Remove the water pump seal from the inside of the water pump housing “2”. • Install the water pump seal with the special tools. • Install the water pump seal with the special tools to the specified depth as shown in the illustration.
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YamahaR125.COM Refer to “CHANGING THE COOLANT” on page 3-15. 3. Check: • Cooling system Leaks → Repair or replace the faulty part. 4. Measure: • Radiator cap opening pressure Below the specified pressure → Replace the radiator cap. Refer to “CHECKING THE RADIATOR” on page 6-3. • Water pump housing plate “2” • Impeller shaft • Impeller shaft retainer “3” T. Impeller shaft retainer bolt 10 Nm (1.0 m·kg, 7.2 ft·lb) LOCTITE® R.
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YamahaR125.COM FUEL SYSTEM FUEL TANK..................................................................................................... 7-1 REMOVING THE FUEL TANK .................................................................. 7-2 CHECKING THE FUEL PUMP BODY....................................................... 7-2 INSTALLING THE FUEL HOSE ................................................................ 7-2 CHECKING THE FUEL PRESSURE ........................................................
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FUEL TANK YamahaR125.COM EAS26620 FUEL TANK Removing the fuel tank 3 T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) 4 T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) 7 1 6 2 5 Order Job/Parts to remove Q’ty Remarks Refer to “GENERAL CHASSIS” on page 4-1. Fuel tank cover 1 Fuel pump coupler 1 Disconnect. 2 Fuel sender coupler 1 Disconnect. 3 Fuel hose connector cover 1 4 Fuel hose 1 5 Fuel overflow hose 1 6 Bracket 1 7 Fuel tank 1 Disconnect.
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FUEL TANK YamahaR125.COM EAS26630 ECA5D71032 REMOVING THE FUEL TANK 1. Extract the fuel in the fuel tank through the fuel tank filler hole with a pump. 2. Remove: • Fuel hose connector cover “1” 3. Disconnect: • Fuel hose “2” CAUTION: When installing the fuel hose, make sure that it is securely connected, and that the fuel hose connector cover is in the correct position, otherwise the fuel hose will not be properly installed.
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YamahaR125.COM 2 1 b. Connect the pressure gauge “3” and fuel pressure adapter “4”. Pressure gauge 90890-03153 YU-03153 Fuel pressure adapter 90890-03181 2 4 3 c. Start the engine. d. Measure the fuel pressure. Output pressure 250.0 kPa (36.3 psi) (2.50 kgf/cm²) Faulty → Replace the fuel tank (with fuel pump). e. Connect the fuel hose and install the fuel hose connector cover. Refer to “INSTALLING THE FUEL HOSE” on page 7-2.
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THROTTLE BODY YamahaR125.COM EAS26970 THROTTLE BODY Removing the throttle body T. 1 R. 12 Nm (1.2 m • kg, 8.7 ft • Ib) T. R. LT 7 Nm (0.7 m • kg, 5.1 ft • Ib) 2 4 5 New 11 E 7 10 3 LS New 8 T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) 8 T. R. Order 2 Nm (0.2 m • kg, 1.4 ft • Ib) Job/Parts to remove 9 6 Q’ty Remarks Fuel tank Refer to “FUEL TANK” on page 7-1. Air filter case Refer to “GENERAL CHASSIS” on page 4-1. 1 Fuel hose 1 2 Fuel injector coupler 1 Disconnect.
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THROTTLE BODY YamahaR125.COM Removing the throttle body T. 1 R. 12 Nm (1.2 m • kg, 8.7 ft • Ib) T. R. LT 7 Nm (0.7 m • kg, 5.1 ft • Ib) 2 4 5 New 11 E 7 10 3 LS New 8 T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) 8 T. R. Order 11 2 Nm (0.2 m • kg, 1.4 ft • Ib) Job/Parts to remove Q’ty Intake manifold 9 6 Remarks 1 For installation, reverse the removal procedure.
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THROTTLE BODY YamahaR125.COM EAS5D71025 EAS5D71028 REMOVING THE THROTTLE BODY 1. Extract the fuel in the fuel tank through the fuel tank filler hole with a pump. 2. Disconnect: • Fuel hose CHECKING THE FUEL INJECTOR 1. Check: • Fuel injector Damage → Replace. EAS26990 EWA5D71003 CHECKING THE THROTTLE BODY 1. Check: • Throttle body Cracks/damage → Replace the throttle body. 2. Check: • Fuel passages Obstruction → Clean. WARNING Cover the fuel hose connections with a cloth when disconnecting them.
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YamahaR125.COM THROTTLE BODY 1 a b 3. Install: • Throttle body NOTE: Align the projection “a” on the throttle body with the slot “b” in the throttle body joint. a b 4. Adjust: • Throttle cable free play Refer to “ADJUSTING THE THROTTLE CABLE FREE PLAY” on page 3-6. 5.
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YamahaR125.COM 1. Air induction system hose (air filter case to reed valve assembly) 2. Air induction system reed valve assembly 3.
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AIR INDUCTION SYSTEM YamahaR125.COM Removing the air induction system reed valve assembly 3 T. R. 10 Nm (1.0 m • kg, 7.2 ft • Ib) 2 1 Order Job/Parts to remove Q’ty Remarks Rider seat/Right side cover Refer to “GENERAL CHASSIS” on page 4-1. Fuel tank Refer to “FUEL TANK” on page 7-1.
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YamahaR125.COM EAS27060 CHECKING THE AIR INDUCTION SYSTEM Air injection The air induction system burns unburned exhaust gases by injecting fresh air (secondary air) into the exhaust port, reducing the emission of hydrocarbons. When there is negative pressure at the exhaust port, the reed valve opens, allowing secondary air to flow into the exhaust port. The required temperature for burning the unburned exhaust gases is approximately 600 to 700 °C (1112 to 1292 °F). 1.
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YamahaR125.COM ELECTRICAL SYSTEM IGNITION SYSTEM ......................................................................................... 8-1 CIRCUIT DIAGRAM .................................................................................. 8-1 TROUBLESHOOTING .............................................................................. 8-3 ELECTRIC STARTING SYSTEM .................................................................... 8-5 CIRCUIT DIAGRAM .....................................................
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YamahaR125.COM ELECTRICAL COMPONENTS...................................................................... 8-57 CHECKING THE SWITCHES ................................................................. 8-59 CHECKING THE BULBS AND BULB SOCKETS ................................... 8-62 CHECKING THE FUSES ........................................................................ 8-63 CHECKING AND CHARGING THE BATTERY....................................... 8-64 CHECKING THE RELAYS ...................................
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8-1 L/Y Gy Gy/R Gy/B O/W Y/W Sb/W SUB-WIRE HARNESS WIRE HARNESS WIRE HARNESS SUB-WIRE HARNESS Br SUB-WIRE HARNESS WIRE HARNESS Y (BLACK) (BLACK) Br Y Ch Dg B/W B/W Dg Ch C Sb G/W Y/L Y/L G/W Sb B W W W R Gy/B Br/L L/B R Sb/W Y/W O/W (BLUE) (BLUE) A B L/B B B 8 7 R/B L/B (BLACK) OFF ON 5 1 Gy/B Gy/R Gy B B L/B L/B (RED) (RED) R/B R Br/L L/Y L/B Br/L R L/B L/Y W W R W W W R W W Gy/B 2 R R B Gy/R L Gy 67 66 65 64 6 W W W B 3 Gy/B Br/L Br/L
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YamahaR125.COM 2. Crankshaft position sensor 4. Main fuse 5. Main switch 8. Sidestand switch 9. Battery 17.Engine stop switch 23.Lean angle sensor 25.ECU (engine control unit) 26.Ignition coil 27.Spark plug 64.
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IGNITION SYSTEM YamahaR125.COM EAS27120 TROUBLESHOOTING The ignition system fails to operate (no spark or intermittent spark). NOTE: • Before troubleshooting, remove the following part(s): 1. Seats 2. Fuel tank 3. Right side cover 4. Left side panel 5. Left upper side cowling 1. Check the fuses. (Main and ignition) Refer to “CHECKING THE FUSES” on page 8-63. NG → Replace the fuse(s). OK ↓ 2. Check the battery. Refer to “CHECKING AND CHARGING THE BATTERY” on page 8-64. NG → • Refill battery fluid.
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YamahaR125.COM 8. Check the main switch. Refer to “CHECKING THE SWITCHES” on page 8-59. IGNITION SYSTEM NG → Replace the main switch. OK ↓ 9. Check the engine stop switch. Refer to “CHECKING THE SWITCHES” on page 8-59. NG → The engine stop switch is faulty. Replace the right handlebar switch. OK ↓ 10.Check the sidestand switch. Refer to “CHECKING THE SWITCHES” on page 8-59. NG → Replace the sidestand switch. OK ↓ 11.Check the lean angle sensor. Refer to “CHECKING THE LEAN ANGLE SENSOR” on page 8-69.
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L/B 8-5 L/Y Gy Gy/R Gy/B O/W Y/W Sb/W SUB-WIRE HARNESS WIRE HARNESS WIRE HARNESS SUB-WIRE HARNESS Br SUB-WIRE HARNESS WIRE HARNESS Y (BLACK) (BLACK) Br Y Ch Dg B/W B/W Dg Ch C Sb G/W Y/L Y/L G/W Sb B W W W R Gy/B Br/L L/B R Sb/W Y/W O/W (BLUE) (BLUE) A B L/B B B 8 R/B L/B (BLACK) OFF ON 5 1 Gy/B Gy/R Gy B B L/B 7 (RED) (RED) R/B R Br/L L/Y L/B Br/L R L/B L/Y W W R W W W R W W Gy/B 2 R B R Gy/B Gy/R L 67 66 65 64 6 W W W B 3 Gy Br/L Br/L
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YamahaR125.COM ELECTRIC STARTING SYSTEM 4. Main fuse 5. Main switch 7. Clutch switch 8. Sidestand switch 9. Battery 10.Starter relay 11.Starter motor 12.Starting circuit cut-off relay 13.Diode 14.Neutral switch 16.Start switch 17.Engine stop switch 64.
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YamahaR125.COM ELECTRIC STARTING SYSTEM EAS27180 STARTING CIRCUIT CUT-OFF SYSTEM OPERATION If the engine stop switch is set to “ ” and the main switch is set to “ON” (both switches are closed), the starter motor can only operate if at least one of the following conditions is met: • The transmission is in neutral (the neutral switch is closed). • The clutch lever is pulled to the handlebar (the clutch switch is closed) and the sidestand is up (the sidestand switch is closed).
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YamahaR125.COM ELECTRIC STARTING SYSTEM a. WHEN THE TRANSMISSION IS IN NEUTRAL b. WHEN CLUTCH LEVER IS PULLED TO THE HANDLEBAR AND THE SIDESTAND IS UP 1. Battery 2. Main fuse 3. Main switch 4. Ignition fuse 5. Engine stop switch 6. Starting circuit cut-off relay 7. Clutch switch 8. Sidestand switch 9. Diode 10. Neutral switch 11. Start switch 12. Starter relay 13.
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YamahaR125.COM ELECTRIC STARTING SYSTEM EAS27190 TROUBLESHOOTING The starter motor fails to turn. NOTE: • Before troubleshooting, remove the following part(s): 1. Seats 2. Fuel tank 3. Left lower side cowling 4. Left upper side cowling 1. Check the fuses. (Main and ignition) Refer to “CHECKING THE FUSES” on page 8-63. NG → Replace the fuse(s). OK ↓ 2. Check the battery. Refer to “CHECKING AND CHARGING THE BATTERY” on page 8-64. NG → • Refill battery fluid. • Clean the battery terminals.
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YamahaR125.COM 8. Check the main switch. Refer to “CHECKING THE SWITCHES” on page 8-59. ELECTRIC STARTING SYSTEM NG → Replace the main switch. OK ↓ 9. Check the engine stop switch. Refer to “CHECKING THE SWITCHES” on page 8-59. NG → The engine stop switch is faulty. Replace the right handlebar switch. OK ↓ 10.Check the neutral switch. Refer to “CHECKING THE SWITCHES” on page 8-59. NG → Replace the neutral switch. OK ↓ 11.Check the sidestand switch. Refer to “CHECKING THE SWITCHES” on page 8-59.
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8-11 B B L/B L/B B (BLUE) (BLUE) L/B R/B L/B (BLACK) OFF ON 5 1 2 B B 8 7 (RED) (RED) R/B R Br/L L/Y L/B Br/L R L/B L/Y W W R W W W R W W Gy/B L/Y Br/L L/B R W W W R Gy/B Br/L Br/L Br/L R W W W R 66 65 64 6 W W W B 3 Br R/Y R/B R/W B R R R R Y/W A Y/W A Sb/W B B 9 R Sb/W 4 O/W A O/W B R R R R R/W Sb B Sb R R/W L/B R/B G/W B G/W 11 R R/W Y/L B Y/L R/B L/B R/B L/B R/B L/B R/W L/B R/B R 10 12 R/W B R/Y L/B R/Y 15
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YamahaR125.COM 1. 3. 4. 9.
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YamahaR125.COM CHARGING SYSTEM EAS27230 TROUBLESHOOTING The battery is not being charged. NOTE: • Before troubleshooting, remove the following part(s): 1. Rider seat 2. Left side panel 3. Left lower side cowling 1. Check the fuse. (Main) Refer to “CHECKING THE FUSES” on page 8-63. NG → Replace the fuse. OK ↓ 2. Check the battery. Refer to “CHECKING AND CHARGING THE BATTERY” on page 8-64. NG → • Refill battery fluid. • Clean the battery terminals. • Recharge or replace the battery. OK ↓ 3.
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8-15 L/Y Gy Gy/R Gy/B O/W Y/W Sb/W SUB-WIRE HARNESS WIRE HARNESS WIRE HARNESS SUB-WIRE HARNESS Br SUB-WIRE HARNESS WIRE HARNESS Y (BLACK) (BLACK) Br Y Ch Dg B/W B/W Dg Ch C Sb G/W Y/L Y/L G/W Sb B W W W R Gy/B Br/L L/B R Sb/W Y/W O/W (BLUE) (BLUE) A B L/B B B 8 7 R/B L/B (BLACK) OFF ON 5 1 Gy/B Gy/R Gy B B L/B L/B (RED) (RED) R/B R Br/L L/Y L/B Br/L R L/B L/Y W W R W W W R W W Gy/B 2 R R B Gy/R L Gy 67 66 65 64 6 W W W B 3 Gy/B Br/L Br/
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YamahaR125.COM 4. Main fuse 5. Main switch 9. Battery 25.ECU (engine control unit) 36.License plate light 37.Tail/brake light 44.Headlight relay 46.Pass switch 47.Dimmer switch 51.Headlight (low beam) 52.Auxiliary light 54.Headlight (high beam) 58.Meter light 60.High beam indicator light 64.Ignition fuse 65.Headlight fuse 66.
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YamahaR125.COM LIGHTING SYSTEM EAS27260 TROUBLESHOOTING Any of the following fail to light: headlight, high beam indicator light, taillight, license plate light, auxiliary light or meter light. NOTE: • Before troubleshooting, remove the following part(s): 1. Seats 2. Fuel tank 1. Check the condition of each bulb and bulb socket. Refer to “CHECKING THE BULBS AND BULB SOCKETS” on page 8-62. NG → Replace the bulb(s) and bulb socket(s). OK ↓ 2. Check the fuses.
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YamahaR125.COM 8. Check the entire lighting system wiring. Refer to “CIRCUIT DIAGRAM” on page 8-15. LIGHTING SYSTEM NG → Properly connect or repair the lighting system wiring. OK ↓ Replace the ECU or meter assembly.
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8-19 L/Y Gy Gy/R Gy/B O/W Y/W Sb/W SUB-WIRE HARNESS WIRE HARNESS WIRE HARNESS SUB-WIRE HARNESS Br SUB-WIRE HARNESS WIRE HARNESS Y (BLACK) (BLACK) Br Y Ch Dg B/W B/W Dg Ch C Sb G/W Y/L Y/L G/W Sb B W W W R Gy/B Br/L L/B R Sb/W Y/W O/W (BLUE) (BLUE) A B L/B B B 8 7 R/B L/B (BLACK) OFF ON 5 1 Gy/B Gy/R Gy B B L/B L/B (RED) (RED) R/B R Br/L L/Y L/B Br/L R L/B L/Y W W R W W W R W W Gy/B 2 R R B Gy/R L Gy 67 66 65 64 6 W W W B 3 Gy/B Br/L Br/
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YamahaR125.COM 4. Main fuse 5. Main switch 9. Battery 14.Neutral switch 25.ECU (engine control unit) 31.Fuel sender 34.Rear brake light switch 35.Front brake light switch 37.Tail/brake light 38.Rear right turn signal light 39.Rear left turn signal light 40.Front right turn signal light 41.Front left turn signal light 42.Turn signal relay 43.Horn 48.Horn switch 49.Turn signal switch 56.Multi-function meter 57.Tachometer 61.Turn signal indicator light 62.Neutral indicator light 64.Ignition fuse 66.
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YamahaR125.COM SIGNALING SYSTEM EAS27290 TROUBLESHOOTING • Any of the following fail to light: turn signal lights, brake light or indicator lights. • The horn fails to sound. • The fuel gauge fails to operate. • The speedometer fails to operate. NOTE: • Before troubleshooting, remove the following part(s): 1. Seats 2. Fuel tank 3. Left upper side cowling 4. Right side panel 5. Left lower side cowling 1. Check the fuses. (Main, ignition, and signaling system) Refer to “CHECKING THE FUSES” on page 8-63.
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SIGNALING SYSTEM YamahaR125.COM 2. Check the horn. Refer to “CHECKING THE HORN” on page 8-71. NG → Replace the horn. OK ↓ 3. Check the entire signaling system wiring. Refer to “CIRCUIT DIAGRAM” on page 8-19. NG → Properly connect or repair the signaling system wiring. OK ↓ This circuit is OK. The tail/brake light fails to come on. 1. Check the front brake light switch. Refer to “CHECKING THE SWITCHES” on page 8-59. NG → Replace the front brake light switch. OK ↓ 2. Check the rear brake light switch.
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YamahaR125.COM 4. Check the entire signaling system wiring. Refer to “CIRCUIT DIAGRAM” on page 8-19. SIGNALING SYSTEM NG → Properly connect or repair the signaling system wiring. OK ↓ Replace the meter assembly. The neutral indicator light fails to come on. 1. Check the neutral switch. Refer to “CHECKING THE SWITCHES” on page 8-59. NG → Replace the neutral switch. OK ↓ 2. Check the entire signaling system wiring. Refer to “CIRCUIT DIAGRAM” on page 8-19.
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8-25 L/Y Gy Gy/R Gy/B O/W Y/W Sb/W SUB-WIRE HARNESS WIRE HARNESS WIRE HARNESS SUB-WIRE HARNESS Br SUB-WIRE HARNESS WIRE HARNESS Y (BLACK) (BLACK) Br Y Ch Dg B/W B/W Dg Ch C Sb G/W Y/L Y/L G/W Sb B W W W R Gy/B Br/L L/B R Sb/W Y/W O/W (BLUE) (BLUE) A B L/B B B 8 7 R/B L/B (BLACK) OFF ON 5 1 Gy/B Gy/R Gy B B L/B L/B (RED) (RED) R/B R Br/L L/Y L/B Br/L R L/B L/Y W W R W W W R W W Gy/B 2 R R B Gy/R L Gy 67 66 65 64 6 W W W B 3 Gy/B Br/L Br/
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YamahaR125.COM 4. Main fuse 5. Main switch 6. Radiator fan motor fuse 9. Battery 22.Coolant temperature sensor 25.ECU (engine control unit) 32.Radiator fan motor relay 33.Radiator fan motor 59.Coolant temperature warning light 64.Ignition fuse 66.
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YamahaR125.COM COOLING SYSTEM EAS27320 TROUBLESHOOTING NOTE: • Before troubleshooting, remove the following part(s): 1. Rider seat 2. Fuel tank 3. Right upper side cowling 4. Passenger seat 1. Check the fuses. (Main, ignition, and signaling system) Refer to “CHECKING THE FUSES” on page 8-63. NG → Replace the fuse(s). OK ↓ 2. Check the battery. Refer to “CHECKING AND CHARGING THE BATTERY” on page 8-64. NG → • Refill battery fluid. • Clean the battery terminals. • Recharge or replace the battery.
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8-29 L/Y Gy Gy/R Gy/B O/W Y/W Sb/W SUB-WIRE HARNESS WIRE HARNESS WIRE HARNESS SUB-WIRE HARNESS Br SUB-WIRE HARNESS WIRE HARNESS Y (BLACK) (BLACK) Br Y Ch Dg B/W B/W Dg Ch C Sb G/W Y/L Y/L G/W Sb B W W W R Gy/B Br/L L/B R Sb/W Y/W O/W (BLUE) (BLUE) A B L/B B B 8 7 R/B L/B (BLACK) OFF ON 5 1 Gy/B Gy/R Gy B B L/B L/B (RED) (RED) R/B R Br/L L/Y L/B Br/L R L/B L/Y W W R W W W R W W Gy/B 2 R R B Gy/R L Gy 67 66 65 64 6 W W W B 3 Gy/B Br/L Br/
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YamahaR125.COM 2. Crankshaft position sensor 4. Main fuse 5. Main switch 6. Radiator fan motor fuse 8. Sidestand switch 9. Battery 17.Engine stop switch 19.Intake air pressure sensor 20.Intake air temperature sensor 21.Throttle position sensor 22.Coolant temperature sensor 23.Lean angle sensor 24.Self-diagnosis signal connector 25.ECU (engine control unit) 26.Ignition coil 27.Spark plug 28.FID (fast idle solenoid) 29.Fuel injector 30.Fuel pump 32.Radiator fan motor relay 33.Radiator fan motor 63.
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YamahaR125.COM EAS27350 FUEL INJECTION SYSTEM ECU SELF-DIAGNOSTIC FUNCTION The ECU is equipped with a self-diagnostic function in order to ensure that the fuel injection system is operating normally. If this function detects a malfunction in the system, it immediately operates the engine under substitute characteristics and illuminates the engine trouble warning light to alert the rider that a malfunction has occurred in the system.
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FUEL INJECTION SYSTEM YamahaR125.
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YamahaR125.COM FUEL INJECTION SYSTEM Self-Diagnostic Function table Fault code No. Item Symptom Able / unable to start Able / unable to drive 12 Crankshaft position sensor No normal signals are received from the crankshaft position sensor. Unable Unable 13 Intake air pressure sensor (open or short circuit) Intake air pressure sensor: open or short circuit detected. Able Able 14 Intake air pressure sensor (system) Intake air pressure sensor: system Able malfunction (clogged hole).
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YamahaR125.COM The engine operation is not normal but the engine trouble warning light does not come on. 1. Check the operation of the following sensors and actuators in the diagnostic mode. Refer to “Sensor operation table” and “Actuator operation table”. 30: Ignition coil 36: Fuel injector EAS27400 TROUBLESHOOTING METHOD The engine operation is not normal and the engine trouble warning light comes on. 1. Check: • Fault code number ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a.
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YamahaR125.COM FUEL INJECTION SYSTEM EAS27431 DIAGNOSTIC MODE It is possible to monitor the sensor output data or check the activation of actuators with the FI diagnostic tool connected to the vehicle and set to the normal mode or the diagnostic monitoring mode.
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FUEL INJECTION SYSTEM YamahaR125.COM 5. Set the main switch to “OFF” to cancel the normal mode. 6. Disconnect the FI diagnostic tool and connect the self-diagnosis signal connector. Setting the diagnostic mode 1. Set the main switch to “OFF” and the engine stop switch to “ ”. 2. Disconnect the self-diagnosis signal connector “1”, and then connect the FI diagnostic tool “2” as shown. 3. Disconnect the fuel pump coupler. 4. While pressing the “MODE” button, set the main switch to “ON”.
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YamahaR125.COM FUEL INJECTION SYSTEM 9. Set the main switch to “OFF” to cancel the diagnostic mode. 10.Disconnect the FI diagnostic tool and connect the self-diagnosis signal connector. Diagnostic code table Fault code No. Symptom Probable cause of malfunction Diagnostic code No. 12 No normal signals are received from the crankshaft position sensor. • Open or short circuit in wire harness. • Defective crankshaft position sensor. • Malfunction in AC magneto rotor. • Improperly installed sensor.
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YamahaR125.COM Fault code No. Symptom FUEL INJECTION SYSTEM Probable cause of malfunction Diagnostic code No. 42 • Open or short circuit in wire harness. No normal signals are re• Defective speed sensor. ceived from the speed sen- • Malfunction in vehicle speed sensor detect- 07 sor. ed. • Malfunction in ECU. 44 Error is detected while reading or writing on EEPROM. 46 Power supply to the fuel in• Malfunction in the charging system. Refer jection system is not norto “CHARGING SYSTEM” on page 8-11.
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YamahaR125.COM Diagnostic code No. 08 Item FUEL INJECTION SYSTEM FI diagnostic tool display Lean angle sensor • Upright 0.4–1.4 • Overturned 3.7–4.4 09 Fuel system voltage (battery voltage) 0–18.7 Approximately 12.0 20 Sidestand switch 60 61 62 70 • Stand retracted ON • Stand extended OFF Checking method Remove the lean angle sensor and incline it more than 65 degrees. Compare with the actually measured battery voltage. (If the battery voltage is lower, perform recharging.
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FUEL INJECTION SYSTEM YamahaR125.COM Actuator operation table Diagnostic code No. 30 36 51 52 54 Item Actuation Checking method Ignition coil When the “MODE” button is pressed, the ignition coil is actuated five times at onesecond intervals. Illuminates the “WARNING” LED on the FI diagnostic tool. Check the spark five times. • Connect an ignition checker. Fuel injector When the “MODE” button is pressed, the fuel injector is actuated five times at onesecond intervals.
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YamahaR125.COM FUEL INJECTION SYSTEM EAS27471 TROUBLESHOOTING DETAILS This section describes the measures per fault code number displayed on the FI diagnostic tool. Check and service the items or components that are the probable cause of the malfunction following the order given. After the check and service of the malfunctioning part have been completed, reset the FI diagnostic tool display according to the reinstatement method. Fault code No.
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YamahaR125.COM Fault code No. 13 Diagnostic code No. FUEL INJECTION SYSTEM Symptom Intake air pressure sensor: open or short circuit detected. 03 Intake air pressure sensor Order Item/components and probable cause Check or maintenance job 1 Connections • Throttle body sensor assembly coupler • Main wire harness ECU coupler • Check the coupler for any pins Setting the that may have pulled out. main switch to • Check the locking condition of “ON”. the coupler.
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YamahaR125.COM Fault code No. 14 Diagnostic code No. FUEL INJECTION SYSTEM Symptom Intake air pressure sensor: system malfunction (clogged hole). 03 Intake air pressure sensor Order Item/components and probable cause Check or maintenance job 1 Connections • Throttle body sensor assembly coupler • Main wire harness ECU coupler • Check the coupler for any pins Starting the enthat may have pulled out. gine and oper• Check the locking condition of ating it at idle. the coupler.
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YamahaR125.COM Fault code No. 15 Diagnostic code No. FUEL INJECTION SYSTEM Symptom Throttle position sensor: open or short circuit detected. 01 Throttle position sensor Order Item/components and probable cause Check or maintenance job 1 Connections • Throttle body sensor assembly coupler • Main wire harness ECU coupler • Check the coupler for any pins Setting the that may have pulled out. main switch to • Check the locking condition of “ON”. the coupler.
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YamahaR125.COM Fault code No. 16 Diagnostic code No. FUEL INJECTION SYSTEM Symptom Throttle position sensor is stuck. 01 Throttle position sensor Order Item/components and probable cause Check or maintenance job Reinstatement method 1 • Execute the diagnostic mode. (Code No.01) • Replace the throttle body if defective. Refer to “CHECKING THE THROTTLE BODY SENSOR ASSEMBLY” on page 8-73. Starting the engine, operating it at idle, then by racing it. Defective throttle position sensor.
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YamahaR125.COM Fault code No. 21 Diagnostic code No. FUEL INJECTION SYSTEM Symptom Coolant temperature sensor: open or short circuit detected. 06 Coolant temperature sensor Order Item/components and probable cause Check or maintenance job 1 Installed condition of coolant tempera- Check the installed area for ture sensor looseness or pinching. 2 Connected state of connector • Check the coupler for any pins • Coolant temperature sensor coupler that may have pulled out.
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YamahaR125.COM Fault code No. 22 Diagnostic code No. FUEL INJECTION SYSTEM Symptom Intake air temperature sensor: open or short circuit detected. 05 Intake air temperature sensor Order Item/components and probable cause Check or maintenance job 1 Connections • Throttle body sensor assembly coupler • Main wire harness ECU coupler • Check the couplers for any pins Setting the that may have pulled out. main switch to • Check the locking condition of “ON”. the couplers.
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YamahaR125.COM Fault code No. 30 Diagnostic code No. FUEL INJECTION SYSTEM Symptom No normal signal is received from the lean angle sensor. 08 Lean angle sensor Order Item/components and probable cause Check or maintenance job Reinstatement method 1 The vehicle has overturned. Raise the vehicle upright. 2 Installed condition of the lean angle sensor. Check for looseness or pinching.
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YamahaR125.COM Fault code No. 39 Diagnostic code No. FUEL INJECTION SYSTEM Symptom Fuel injector: open or short circuit detected. 36 Fuel injector Order Item/components and probable cause Check or maintenance job 1 Connections • Fuel injector coupler • Main wire harness ECU coupler • Check the couplers for any pins Cranking the that may have pulled out. engine. • Check the locking condition of the couplers. • If there is a malfunction, repair it and connect the coupler securely.
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YamahaR125.COM Fault code No. 42 Diagnostic code No. FUEL INJECTION SYSTEM Symptom No normal signals are received from the speed sensor. 07 Speed sensor Order Item/components and probable cause Check or maintenance job Reinstatement method 1 Connections • Speed sensor coupler • Wire harness ECU coupler • Check the coupler for any pins that may have pulled out. • Check the locking condition of the coupler. • If there is a malfunction, repair it and connect the coupler securely.
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YamahaR125.COM Fault code No. 46 Diagnostic code No. FUEL INJECTION SYSTEM Symptom Power supply to the fuel injection system is not normal. — — Order Item/components and probable cause Check or maintenance job 1 Connections • Main wire harness ECU coupler • Check the coupler for any pins Starting the enthat may have pulled out. gine and oper• Check the locking condition of ating it at idle. the coupler. • If there is a malfunction, repair it and connect the coupler securely. 2 Faulty battery.
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8-53 L/Y Gy Gy/R Gy/B O/W Y/W Sb/W SUB-WIRE HARNESS WIRE HARNESS WIRE HARNESS SUB-WIRE HARNESS Br SUB-WIRE HARNESS WIRE HARNESS Y (BLACK) (BLACK) Br Y Ch Dg B/W B/W Dg Ch C Sb G/W Y/L Y/L G/W Sb B W W W R Gy/B Br/L L/B R Sb/W Y/W O/W (BLUE) (BLUE) A B L/B B B 8 7 R/B L/B (BLACK) OFF ON 5 1 Gy/B Gy/R Gy B B L/B L/B (RED) (RED) R/B R Br/L L/Y L/B Br/L R L/B L/Y W W R W W W R W W Gy/B 2 R R B Gy/R L Gy 67 66 65 64 6 W W W B 3 Gy/B Br/L Br/
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YamahaR125.COM 4. Main fuse 5. Main switch 9. Battery 17.Engine stop switch 25.ECU (engine control unit) 30.Fuel pump 64.
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YamahaR125.COM FUEL PUMP SYSTEM EAS27570 TROUBLESHOOTING If the fuel pump fails to operate. NOTE: • Before troubleshooting, remove the following part(s): 1. Rider seat 2. Fuel tank 1. Check the fuses. (Main and ignition) Refer to “CHECKING THE FUSES” on page 8-63. NG → Replace the fuse(s). OK ↓ 2. Check the battery. Refer to “CHECKING AND CHARGING THE BATTERY” on page 8-64. NG → • Refill battery fluid. • Clean the battery terminals. • Recharge or replace the battery. OK ↓ 3. Check the main switch.
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ELECTRICAL COMPONENTS YamahaR125.
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YamahaR125.COM 1. 2. 3. 4. 5. Main switch Clutch switch Front brake light switch Ignition coil Throttle body sensor assembly (intake air pressure sensor, intake air temperature sensor, throttle position sensor) 6. FID (fast idle solenoid) 7. Rectifier/regulator 8. Lean angle sensor 9. Starting circuit cut-off relay 10. Turn signal relay 11. Radiator fan motor relay 12. Headlight relay 13. ECU (engine control unit) 14. Fuse box 15. Starter relay 16. Battery 17. Rear brake light switch 18.
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ELECTRICAL COMPONENTS YamahaR125.
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YamahaR125.COM 1. Clutch switch 2. Main switch 3. Front brake light switch 4. Sidestand switch 5. Rear brake light switch 6. Neutral switch 7. Turn signal switch 8. Horn switch 9. Dimmer switch 10. Pass switch 11. Engine stop switch 12.
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ELECTRICAL COMPONENTS YamahaR125.COM Check each switch for continuity with the pocket tester. If the continuity reading is incorrect, check the wiring connections and, if necessary, replace the switch. ECA14370 CAUTION: Never insert the tester probes into the coupler terminal slots “a”. Always insert the probes from the opposite end of the coupler, taking care not to loosen or damage the leads.
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ELECTRICAL COMPONENTS YamahaR125.COM 1. Remove: • Bulb EAS27990 CHECKING THE BULBS AND BULB SOCKETS EWA5D71001 WARNING NOTE: Since the headlight bulbs get extremely hot, keep flammable products and your hands away from them until they have cooled down. Do not check any of the lights that use LEDs. Check each bulb and bulb socket for damage or wear, proper connections, and also for continuity between the terminals. Damage/wear → Repair or replace the bulb, bulb socket or both.
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ELECTRICAL COMPONENTS YamahaR125.COM NOTE: Set the pocket tester selector to “Ω × 1”. Pocket tester 90890-03112 Analog pocket tester YU-03112-C b. If the pocket tester indicates “∞”, replace the fuse. Checking the condition of the bulb sockets The following procedure applies to all of the bulb sockets. 1. Check: • Bulb socket (for continuity) (with the pocket tester) No continuity → Replace. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 3. Replace: • Blown fuse ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a.
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YamahaR125.COM ELECTRICAL COMPONENTS 3. Remove: • Battery 4. Check: • Electrolyte level The electrolyte level should be between the minimum level mark “a” and the maximum level mark “b”. Below the minimum level mark → Add distilled water to the proper level. EAS28010 CHECKING AND CHARGING THE BATTERY EWA13290 WARNING Batteries generate explosive hydrogen gas and contain electrolyte which is made of poisonous and highly caustic sulfuric acid.
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YamahaR125.COM • When charging a battery, be sure to remove it from the vehicle. (If charging has to be done with the battery mounted on the vehicle, disconnect the negative lead from the battery terminal.) • To reduce the chance of sparks, do not plug in the battery charger until the battery charger leads are connected to the battery. • Before removing the battery charger lead clips from the battery terminals, be sure to turn off the battery charger.
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YamahaR125.COM ELECTRICAL COMPONENTS EAS28040 CHECKING THE RELAYS Check each switch for continuity with the pocket tester. If the continuity reading is incorrect, replace the relay. Result Continuity (between “3” and “4”) Headlight relay Pocket tester 90890-03112 Analog pocket tester YU-03112-C 3 4 1. Disconnect the relay from the wire harness. 2. Connect the pocket tester (Ω × 1) and battery (12 V) to the relay terminal as shown. Check the relay operation. Out of specification → Replace.
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ELECTRICAL COMPONENTS YamahaR125.COM Turn signal relay input voltage DC 12 V 1 ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Connect the pocket tester (DC 20 V) to the turn signal relay terminal as shown. Br/W Br Pocket tester 90890-03112 Analog pocket tester YU-03112-C b. Set the main switch to “ON”. c. Measure the turn signal relay output voltage. • Positive tester probe → brown “1” • Negative tester probe → ground ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ EAS28050 CHECKING THE DIODE 1.
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YamahaR125.COM 3 ELECTRICAL COMPONENTS Primary coil resistance 2.16–2.64 Ω at 20 °C (68 °F) 1 ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ 2 a. Disconnect the ignition coil connectors from the ignition coil terminals. b. Connect the pocket tester (Ω × 1) to the ignition coil as shown. L/B R/B Sb/W Pocket tester 90890-03112 Analog pocket tester YU-03112-C ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Disconnect the diode from the wire harness. b. Connect the pocket tester (Ω × 1) to the diode terminals as shown. c.
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YamahaR125.COM ELECTRICAL COMPONENTS e. Crank the engine by pushing the start switch “ ” and gradually increase the spark gap until a misfire occurs. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ EAS28120 CHECKING THE CRANKSHAFT POSITION SENSOR 1. Disconnect: • Crankshaft position sensor coupler (from the wire harness) 2. Check: • Crankshaft position sensor resistance Out of specification → Replace the crankshaft position sensor/stator assembly. c. Measure the secondary coil resistance.
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YamahaR125.COM ELECTRICAL COMPONENTS • This check is likely to produce sparks, therefore, make sure no flammable gas or fluid is in the vicinity. Lean angle sensor output voltage Less than 65°: 0.4–1.4 V More than 65°: 3.7–4.4 V ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Connect the lean angle sensor to the wire harness. b. Connect the pocket tester (DC 20 V) to the lean angle sensor coupler as shown. Pocket tester 90890-03112 Analog pocket tester YU-03112-C b. Check the starter motor operation.
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YamahaR125.COM ELECTRICAL COMPONENTS EAS28180 CHECKING THE HORN 1. Check: • Horn resistance Out of specification → Replace. 1 W W Coil resistance 1.15–1.25 Ω at 20 °C (68 °F) 3 W 2 ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Disconnect the horn connectors from the horn terminals. b. Connect the pocket tester (Ω × 1) to the horn terminals. b. Measure the stator coil resistance. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ EAS28170 CHECKING THE RECTIFIER/REGULATOR 1.
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YamahaR125.COM EAS28220 ELECTRICAL COMPONENTS EAS28240 CHECKING THE FUEL SENDER 1. Drain the fuel from the fuel tank. 2. Check: • Fuel sender resistance Out of specification → Replace the fuel sender. CHECKING THE SPEED SENSOR 1. Check: • Speed sensor output voltage Out of specification → Replace. Output voltage reading cycle 0 V to 5.0 V to 0 V to 5.0 V Sender unit resistance (full) 0.0–7.0 Ω Sender unit resistance (empty) 90.0–103.0 Ω ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a.
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YamahaR125.COM ELECTRICAL COMPONENTS 3 1 1 L B 2 2 c. Measure the radiator fan motor movement. d. Slowly heat the coolant, and then let it cool down to the specified temperature. e. Check the coolant temperature sensor resistance. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ EAS28260 CHECKING THE COOLANT TEMPERATURE SENSOR 1. Remove: • Coolant temperature sensor ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 3. Install: • Coolant temperature sensor EWA14130 WARNING T. R.
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YamahaR125.COM b. Measure the throttle position sensor input voltage. Out of specification → Replace or repair the wire harness. ELECTRICAL COMPONENTS Pocket tester 90890-03112 Analog pocket tester YU-03112-C Throttle position sensor input voltage 5V • Positive tester probe → pink/white “1” • Negative tester probe → gray/black “2” c. Connect the digital circuit tester to the terminals of the throttle body sensor assembly coupler as shown.
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YamahaR125.COM Gy/R Y Gy/B 2 1 b. Measure the intake air temperature sensor resistance. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ EAS5D71002 CHECKING THE FID (FAST IDLE SOLENOID) 1. Disconnect: • FID (fast idle solenoid) coupler 2. Check: • FID (fast idle solenoid) resistance ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Disconnect the FID (fast idle solenoid) coupler from the FID. b. Connect the pocket tester (Ω × 10) to the terminals of the FID (fast idle solenoid).
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YamahaR125.COM TROUBLESHOOTING TROUBLESHOOTING..................................................................................... 9-1 GENERAL INFORMATION ....................................................................... 9-1 STARTING FAILURES.............................................................................. 9-1 INCORRECT ENGINE IDLING SPEED .................................................... 9-1 POOR MEDIUM-AND-HIGH-SPEED PERFORMANCE ........................... 9-2 FAULTY GEAR SHIFTING..
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TROUBLESHOOTING YamahaR125.COM Electrical system 1. Battery • Discharged battery • Faulty battery 2. Fuse(s) • Blown, damaged or incorrect fuse • Improperly installed fuse 3. Spark plug • Incorrect spark plug gap • Incorrect spark plug heat range • Fouled spark plug • Worn or damaged electrode • Worn or damaged insulator • Faulty spark plug cap 4. Ignition coil • Cracked or broken ignition coil body • Broken or shorted primary or secondary coils • Faulty spark plug lead 5.
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TROUBLESHOOTING YamahaR125.COM • Foreign object between transmission gears • Improperly assembled transmission • Flooded throttle body • Faulty air induction system Electrical system 1. Battery • Discharged battery • Faulty battery 2. Spark plug • Incorrect spark plug gap • Incorrect spark plug heat range • Fouled spark plug • Worn or damaged electrode • Worn or damaged insulator • Faulty spark plug cap 3.
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TROUBLESHOOTING YamahaR125.COM 2. Engine oil • Incorrect oil level • Incorrect oil viscosity • Inferior oil quality • Damaged brake hose • Oil or grease on the brake disc • Oil or grease on the brake pad • Incorrect brake fluid level Cooling system 1. Coolant • Low coolant level 2. Radiator • Damaged or leaking radiator • Faulty radiator cap • Bent or damaged radiator fin 3.
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YamahaR125.COM EAS28740 WIRING DIAGRAM YZF-R125 2008 1. AC magneto 2. Crankshaft position sensor 3. Rectifier/regulator 4. Main fuse 5. Main switch 6. Radiator fan motor fuse 7. Clutch switch 8. Sidestand switch 9. Battery 10. Starter relay 11. Starter motor 12. Starting circuit cut-off relay 13. Diode 14. Neutral switch 15. Right handlebar switch 16. Start switch 17. Engine stop switch 18. Throttle body sensor assembly 19. Intake air pressure sensor 20. Intake air temperature sensor 21.
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