Service Manual

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N-28 ENGINE SERVICE MANUAL

Table of Contents – Page 1 of 1

GENERAL INFORMATION

SPECIFICATIONS AND TORQUES

SAFETY WARNINGS AND NOTES

PRODUCT IDENTIFICATION NUMBERS

STARTING/STOPPING INSTRUCTIONS

SERVICE/MAINTENANCE INSTRUCTIONS

STORAGE INSTRUCTIONS

TROUBLESHOOTING

ENGINE FAILS TO START

ENGINE STARVES ON ACCELERATION

ENGINE IS HARD TO START

ENGINE STALLS

ENGINE FIRES INTERMITTENTLY

ENGINE DOES NOT PRODUCE MAXIMUM POWER

CARBURETOR FLOODS

ENGINE STOPS AFTER RUNNING BRIEFLY

ENGINE WILL NOT IDLE

ENGINE BACKFIRES OR MISFIRES

ENGINE WILL NOT ACCELERATE

ENGINE LACKS POWER OR STOPS DURING OPERATION

DISASSEMBLY, INSPECTION, & REPAIR

TYPICAL DISASSEMBLY SEQUENCE

MAJOR COMPONENTS (CONT.)

ENGINE

REASSEMBLY

TYPICAL DISASSEMBLY SEQUENCE

ENGINE

MAJOR COMPONENTS

Summary of content (77 pages)

PAGE 1
N-28 ENGINE SERVICE MANUAL Table of Contents – Page 1 of 1 GENERAL INFORMATION SPECIFICATIONS AND TORQUES SAFETY WARNINGS AND NOTES PRODUCT IDENTIFICATION NUMBERS STARTING/STOPPING INSTRUCTIONS SERVICE/MAINTENANCE INSTRUCTIONS STORAGE INSTRUCTIONS TROUBLESHOOTING ENGINE FAILS TO START ENGINE STARVES ON ACCELERATION ENGINE IS HARD TO START ENGINE STALLS ENGINE FIRES INTERMITTENTLY ENGINE DOES NOT PRODUCE MAXIMUM POWER CARBURETOR FLOODS ENGINE STOPS AFTER RUNNING BRIEFLY ENGINE WILL NOT IDLE ENGINE BACKFIRES
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GENERAL INFORMATION General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Disassembly, Inspection, and Repair . . . . . . . . . . . . . . . . . . . 3 Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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GENERAL INFORMATION Table Of Contents 1 SPECIFICATIONS AND TORQUES Engine - All N28 Engines . . . . . . . . . . . . . . . . . . . . . . 1-4 Engine - Units with Serial Number 102084332 to 302010968 Engine - Units with Serial Number 302010969 and Greater . . . 1-4 . . . . 1-3 Fuel and Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 Ignition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 Air Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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GENERAL INFORMATION 1 Safety Warnings and Notes . . . . . . . . . . . . . . . . . . . . . . . . 1-6 Product Identification Numbers . . . . . . Engine Serial Number Significance . Oil and Fuel Recommendations . . . . . . Recommended Oil Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7 1-7 1-7 1-7 Recommended Fuel Type . . . . . . . . . . . . . . . . . . . . . 1-7 Use of Blended Fuels . . . .
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GENERAL INFORMATION SPECIFICATIONS AND TORQUES 1 Engine Specifications Item Engine Type Air-cooled. 2-cycle, Third Port Displacement 1.7 cu. in. (28.5 cc) Bore 1.31 in. (33.27 mm) 1.31 in. (33.27 mm) Stroke 1.28 in. (32.51 mm) 1.28 in. (32.51 mm) Average Compression 115-125 lbs. (52-57 kg) Piston Ring(s) Side Clearance 0.004 in. max (0.101 mm) Piston Ring Width (S/N 102084332 to 302010968) 0.060 in. (1.6 mm) Piston Ring Width (S/N 302010969 and Greater) 0.046 in. (1.
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GENERAL INFORMATION SPECIFICATIONS AND TORQUES (cont.) 1 Torque Specifications Item Air Filter Cover Mounting Screws 18-22 in•lb (2.0-2.5 N•m) Carburetor/Choke Plate Mounting Screws (Initial Torque) 13-17 in•lb (1.5-1.9 N•m) Carburetor/Choke Plate Mounting Screws (Retorque) 23-27 in•lb (2.6-3.0 N•m) Throttle Wire Swivel Screw (S/N 102084332 to 302010968) 9-12 in•lb (1.0-1.4 N•m) Carburetor Spacer Screws 55-65 in•lb (6.2-7.3 N•m) Clutch Cover Mounting Screws 35-40 in•lb (3.9-4.
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GENERAL INFORMATION 1 SAFETY WARNINGS AND NOTES WARNING: The purpose of safety symbols is to attract your attention to possible dangers. The safety symbols and the explanations with them deserve your careful attention and understanding. The safety warnings do not by themselves eliminate any danger. The instructions or warnings they give are not substitutes for proper accident prevention measures. Gasoline may be present in the fuel tank, carburetor, fuel line, or crankcase.
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GENERAL INFORMATION PRODUCT IDENTIFICATION NUMBERS When ordering parts, or in any communication involving an engine or product, always give the: Recommended Oil Type Toro 2-cycle oil is recommended for use in these engines (Figure 1-2). If another brand of 2-cycle oil is used, use a high quality oil that is formulated for small 2-cycle air-cooled engines. • Model Number and • Serial Number These numbers are located on a decal (or decals) affixed to the unit (Figure 1-1).
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GENERAL INFORMATION Use of Blended Fuels 1 If you choose to use a blended fuel or its use is unavoidable, the following precautions are recommended: 1. Always use fresh fuel mixed according to the instructions in this section. 2. Use the special additive Alcohol Protector® (by Gold Eagle) or equivalent to inhibit corrosion and reduce oil/fuel separation (mix as directed). 3. Always agitate the fuel mix before fueling unit. 4. Drain the fuel tank and run engine dry before storing unit.
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GENERAL INFORMATION STARTING/STOPPING INSTRUCTIONS 5. Squeeze the throttle trigger to “FULL THROTTLE” (Figure 1-5). Hold or lock the throttle in this position. To Start the Engine 1. Make sure the switch is in the “START” or “ON” position (Figure 1-3). Figure 1-5. Typical Throttle Control. 3.6069.005 6. Pull the starter rope BRISKLY until you hear the engine sound like it wants to run (normally 2 to 5 pulls). 3.6069.003. Figure 1-3. Typical Ignition Switch. 2.
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GENERAL INFORMATION SERVICE/MAINTENANCE INSTRUCTIONS 1 Air Filter NOTE: CLEAN AND RE-OIL THE AIR FILTER EVERY 10 HOURS OF OPERATION. The air filter is one of the most important areas to maintain. If it is not maintained as follows, severe engine damage can result: 1 Remove the air filter from the carburetor/air filter cover assembly. Refer to Part 3 - Engine Disassembly. 2. Wash the air filter in detergent and water (Figure 1-6). Rinse the air filter thoroughly in clean water and allow it to dry. 3.
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GENERAL INFORMATION Never touch electrical wires or components while the engine is running. They can be sources of electrical shock. 1. Before removing the spark plug, clean the area around the base of the spark plug to keep dirt and debris out of the engine. 2. Disconnect the spark plug wire and remove the spark plug from engine. 3. Inspect the spark plug for carbon buildup and clean if necessary. Replace the plug if it is badly burnt or if reuse is questionable.
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GENERAL INFORMATION 1 (H) High Speed Mixture (L) Idle Mixture Needle Idle Speed Screw 5. Final High Speed Mixture Setting: Squeeze the throttle trigger to the FULL (WIDE OPEN) THROTTLE position. Turn the high speed mixture needle clockwise or counterclockwise to set the high speed RPM: 6,800 to 7,200. 6. Release the throttle trigger and let the engine idle. If the engine stops, turn the idle speed screw clockwise 1/8 turn at a time until the engine idles. 7.
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GENERAL INFORMATION 3. If the high speed RPM exceeds 8,800 RPM, the governor assembly in the carburetor must be cleaned or replaced and the carburetor readjusted. 5. Store the unit in a dry, well ventilated area. 1 To Reactive Unit for Service 1. Remove the spark plug and drain the oil from the cylinder by slowly pulling the starter rope. STORAGE INSTRUCTIONS WARNING: Explosive Fuel! Gasoline is extremely flammable and its vapors can explode if ignited.
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GENERAL INFORMATION 1 Figure 1-11. Clutch Tool P/N 147337. 3.6069.011 Figure 1-12. Clutch Tool for Professional N28 Engines. 3.6069.012 Figure 1-13. Flywheel Holder, P/N 612470. 3.6069.
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TROUBLESHOOTING General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 Disassembly, Inspection, and Repair . . . . . . . . . . . . . . . . . . . 3 Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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TROUBLESHOOTING Table of Contents Engine Fails to Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 Engine Starves on Acceleration . . . . . . . . . . . . . . . . . . . . . . 2-4 Engine is Hard to Start . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 2 Engine Stalls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 Engine Fires Intermittently . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 Engine Does Not Produce Maximum Power . . . . . . . . . . . . . .
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TROUBLESHOOTING When difficulties occur, be sure to check for simple causes which, at first, may seem too obvious to beconsidered. A starting problem, for example, could be caused by an empty fuel tank. The following table lists some common causes of operating troubles and the possible causes and remedies. Engine Fails to Start 2 Possible Cause Remedy Ignition switch OFF Turn switch ON Out of fuel or water in fuel Drain tank and blow out fuel lines to remove water.
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TROUBLESHOOTING Engine Starves on Acceleration 2 Possible Cause Remedy Plugged fuel filter Replace fuel filter Improperly adjusted carburetor Adjust carburetor about 1/8 turn Engine is Hard to Start Possible Cause Remedy Fouled, improperly gapped, or broken spark plug Clean or replace spark plug; set gap to 0.018-0.023 in. (0.45 to 0.
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TROUBLESHOOTING Engine Fires Intermittently Possible Cause Remedy Fouled, improperly gapped, or broken spark plug Clean or replace spark plug; set gap to 0.018-0.023 in. (0.45 to 0.58 mm) Incorrect air gap between flywheel and ignition module Set ignition module air gap to 0.010-0.015 inch (0.254-0.
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TROUBLESHOOTING Engine Stops After Running Briefly 2 Possible Cause Remedy Partially plugged fuel tank cap vent Clean fuel tank cap vent Dirty or plugged air filter Clean or replace air filter Water in fuel mixture Drain tank and blow out lines Air leak at carburetor base gasket Tighten carburetor mounting fasteners or replace carburetor base gaskets Dirty carburetor fuel inlet needle or passage Replace fuel inlet needle or clean out carburetor Faulty carburetor diaphragm Replace diaphragm L
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TROUBLESHOOTING Engine Will Not Accelerate Possible Cause Remedy Carburetor improperly adjusted Adjust carburetor Air filter clogged Clean or replace air filter Spark plug fouled Clean or replace spark plug; set gap to 0.018-0.023 in. (0.45 to 0.
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DISASSEMBLY, INSPECTION, & REPAIR General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Disassembly, Inspection, and Repair . . . . . . . . . . . . . . . . . . 3 Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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DISASSEMBLY, INSPECTION, & REPAIR Table Of Contents Typical Disassembly Sequence . . . . . . . . . . . . . . . . . . . . . . 3-4 Major Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 Drain Fuel From Tank . . . . . . . . . . . . . . . . . . . . . . . . 3-5 Remove Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 Standard N28 Engines . . . . . . . . . . . . . . . . . . . . . 3-5 Professional N28 Engines . Remove Styling Cover Remove Air Filter 3 . . . . . . . . . .
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DISASSEMBLY, INSPECTION, & REPAIR Muffler Inspection and Cleaning . . . . . . . . . . . . . . . . . . 3-18 Muffler Reassembly . . . . . . . . . . . . . . . . . . . . . . . . 3-19 Remove Clutch . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19 Standard N28 Engines . . . . . . . . . . . . . . . . . . . . 3-19 Professional N28 Engines Clutch Inspection . . . . . . . . . . . . . . . . . . 3-20 . . . . . . . . . . . . . . . . . . . . . . . . . 3-21 Remove Starter Housing . . . . . . . . . . . . .
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DISASSEMBLY, INSPECTION, & REPAIR Typical Disassembly Sequence The following sequence is suggested for complete engine disassembly, inspection, and repair. This procedure can be varied to accommodate individual requirements for disassembly and repair. Clean all parts thoroughly as the engine is disassembled. Only clean parts can accurately be inspected and gauged for wear or damage. There are many commercially available cleaners that will quickly remove oil and grime from engine parts.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) Drain Fuel From Tank WARNING: WARNING: Explosive Fuel! Gasoline may be present in the fuel tank, carburetor, fuel lines, and crankcase. Gasoline is extremely flammable, and its vapors can explode if ignited. Keep sparks, flames, and other sources of ignition away from the engine. Do not smoke while servicing the engine. Never use gasoline as a cleaning agent. EXPLOSIVE FUEL 3 1.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) 3. For units with serial number 302010969 and greater, remove the Z-bend of throttle cable from the hole in the carburetor throttle lever. 4. Disconnect the lead wires from the ignition switch. NOTE: The location of the lead wires and the removal instructions will vary from model to model. 2.6071.016 3 Anti-Rotation Screw 5. Remove the anti-rotation screw from the drive housing. 6. Loosen clamp nut and bolt. 7.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) 3. Disconnect the lead wires from the ignition switch. NOTE: The location of the lead wires and the removal instructions will vary from model to model. 3.6069.003 3 Anti-Rotation Screw 4. Remove the anti-rotation screw from the clutch housing/drum assembly. 5. Loosen clamp screw. 6. Remove engine from the drive housing (boom). Clamp Screw 3.6071.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) Remove Air Filter Use the following procedures to remove the air filter cover and element. Service the element as instructed in Part 1 - General Information. 1. Remove the screws securing the air filter cover. Remove the air filter cover assembly from the air filter base. 3.6071.019 3 2. Remove the air filter element from the air filter cover. 3.6071.020 Remove Choke/Carburetor 1.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) 3. Remove the fuel line from the carburetor fuel inlet fitting. 4. Remove the fuel line from the fuel outlet fitting on carburetor (to primer bulb). Fuel Inlet Fitting 5. Remove the carburetor and carburetor gasket. Fuel Outlet Fitting 2.6071.024 3 Remove Primer Bulb 1. Remove the fuel lines from the fittings on primer bulb. 2. Squeeze the mounting tabs on the back of the bulb, and pull the bulb out from the front of the air filter base.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) 2. Remove the fuel metering cover screws and cover. 2.6071.024 3 3. Remove the fuel metering diaphragm and gasket. 2.6071.025 4. Remove the screw securing the metering lever hinge pin in carburetor body. Remove the metering lever, hinge pin, metering lever spring, and fuel inlet needle. NOTE: These components are under spring tension. Remove them carefully to prevent loss. Make sure the spring is not stretched. 2.6071.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) Fuel pump Side 1. Remove the idle speed adjusting screw and spring from fuel pump cover. 2. Remove the fuel pump cover screw and cover. 2.6047.027 3 3. Remove the fuel pump cover gasket and pump diaphragm. NOTE: Further disassembly to remove the throttle plate, throttle lever, welch plugs, fuel inlet screen, etc., is not recommended. 2.6071.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) 1. Inspect the tips of the high speed mixture needle, idle mixture needle, and fuel inlet needle for wear or damage. Replace the needles if necessary. 3.6179.165 3 2. Gaskets and diaphragms eventually deteriorate and become stiff with age and use. It is good practice to replace gaskets and diaphragms for each repair.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) 2. Place a straight edge across the carburetor body. Use a wire feeler gauge to measure the distance between the the straight edge and the top of the fuel metering lever. The fuel metering lever should be 0.060-0.070 in. (1.52-1.78 mm) below the straight edge. 2.6071.029 DEPRESS HERE THEN PUSH NEEDLE HERE Adjust the metering lever. If the lever is adjusted too high, the engine will run rich.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) 4. Make sure there are no wrinkles in the metering diaphragm. Install the metering cover and screws. Tighten the the screws securely. 2.6071.033 3 5. Install the high speed mixture (H) and idle mixture (L) adjusting needles and springs. Turn both needles clockwise until they are lightly seated.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) 2. Install the fuel pump cover and cover screw. Tighten the screw securely. 3. If necessary, install the idle speed adjusting screw and spring. Turn the adjusting screw clockwise until it just touches the throttle lever; then continue turning 2 full turns. 2.6071.036 3 Final Carburetor Adjustment Make final adjustments to the carburetor when the unit is fully reassembled. Refer to “Carburetor Adjustment” in Part 1 - General Information. 3.6069.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) Remove Rear Engine Cover 1. Remove the two (2) screws securing the rear cover to the starter housing and crankcase. 2. Remove the rear engine cover. 2.6071.039 3 Remove Fuel Tank Bracket, Fuel Tank, and Heat Shield 1. Remove the two (2) screws from the fuel tank bracket. 2. Remove the bracket, fuel tank, and heat shield. 3. Remove the rubber fuel tank mounting pads. 2.6071.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) Fuel Line and Filter Removal This unit has two fuel lines to the fuel tank. The clear line provides normal fuel flow. The blue line provides a return line for excess fuel flow during the primer operation. The blue (primer) line is removed/ installed in the same manner as the fuel line except it does not have a fuel filter. To remove the fuel lines and fuel filter: 1.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) Remove Muffler 1. Remove the muffler mounting bolts. 2. Remove the muffler and gasket. Discard the old gasket. 3.6071.045 3 Exhaust Exit Tube Removal 1. Remove the screws securing the exhaust exit tube to the muffler body. 2. Remove the exhaust exit tube and gasket. 2.6071.043 Muffler Inspection and Cleaning The muffler should be removed periodically to inspect for excessive carbon build-up.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) 2. Inspect the baffle inside muffler for carbon build-up. Clean baffle by scraping carbon as required. Use a piece of wire to clear obstructions from the small holes in baffle. 3. Inspect the muffler mounting holes for elongation. Replace the muffler if the holes are elongated. 3.6071.045 3 Muffler Reassembly 1. Install a new gasket and the exhaust exit tube. Secure the tube with two (2) screws. Torque the screws to 15-25 in•lb (1.7-2.8 N•m).
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) Clutch Tool 2. Install flywheel holder, P/N 612470 or 180919. 3. Using clutch tool, P/N 147337 or 180918, remove the clutch rotor. 4. Remove the spacer sleeve from crankshaft. Flywheel Holder 2.6071.047 3 Professional N28 Engines 1. Remove the four (4) screws securing the clutch housing/drum assembly to starter housing. Remove the clutch housing/drum assembly. 2. Install flywheel holder, P/N 612470 or 180919. 2.6071.048 3.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) Clutch Tool 4. Using the clutch tool for professional N28 engines, remove the clutch rotor. 5. Remove the spacer sleeve from crankshaft. 2.6071.050 3 Clutch Inspection 1. Check the clutch rotor, shoes, and spring for wear or damage. Replace if necessary. 2.6078.088 Remove Starter Housing 1. If necessary, disconnect the spark plug wire from spark plug and remove the spark plug. 2. Remove the screws securing the starter housing.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) Starter Disassembly, Repalr, and Reassembly WARNING: Sprlng under tension! The rope starter on these engines contains a flat wire spring that is under tension. Wear eye and hand protection when replacing worn or broken spring, in case it should uncoil as it is handled. Allow spring tension to be completely relieved and make sure pulley disengages from spring before removing the pulley retainer, pulley, and starter spring from housing. 2.6060.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) 3. Pull the rope out to its full length and let it return until the pull handle rests against the starter housing. NOTE: Do not add any more tension than is necessary to make the pull handle return against the starter housing. Adding excessive spring tension can cause the spring to break. If spring pressure is weak and adjustment will not enable the pull handle to return against the starter housing, replace the spring. 2.6078.089 3 Disassembly 1.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) 4. If necessary, carefully remove the starter spring from the starter housing using a needle-nose pliers. NOTE: Once the starter spring is removed from the starter housing, a service replacement spring (prewound and contained in a spring retainer) should be used to reassemble the starter. Reinstallation of the old starter spring is not recommended. 2.6071.055 3 5. Remove the starter rope from the pulley. 6.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) Reassembly 1. Install the starter spring into the starter housing as follows: a. Orient the replacement starter spring so the spring windings are clockwise (the open end of spring hook is to the left). 2.6071.057 3 b. Grasp the spring near the spring hook with a needle-nose pliers and carefully remove the spring retainer. 2.6071.058 c. Place the spring into the starter housing.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) 2. Insert the rope through the hole in starter pulley. Tie a single knot in the rope approximately 0.5 in. (12.7 mm) from the end. 3. Pull the rope tight, pulling the knot into the pocket in the pulley. Using a screwdriver, or similar tool, push the end of the rope into the slot in the pulley. 2.6071.060 3 4. Hold the pulley with the pawl engagement teeth towards you. Wrap the rope around the pulley in the clockwise direction.
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DISASSEMBLY, INSPECTION, & REPAIR MAJOR COMPONENTS (cont.) 9. Install the pulley retainer and screw. Torque the screws to 20-30 in•lb (2.3-3.4 N•m). 10. Pull the rope out to its full length and let it return. Check the spring tension and adjust as necessary. Refer to “Adding Starter Spring Tension” above. 2.6071.053 3 ENGINE Remove Ignition Module 1. Make sure the spark plug wire and the lead wires to the ignition module are disconnected. 2.
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DISASSEMBLY, INSPECTION, & REPAIR ENGINE (cont.) 2. Remove the flywheel from the crankshaft. 3. Remove the flywheel key from crankshaft. 2.6071.066 3 Flywheel Inspection and Repair Inspect the flywheel for the following conditions: • Missing, broken, or cracked fins. • Oval shaped pawl pin holes. • Broken, damaged or missing springs, pawls, or pawl pins. Freedom of movement of pawls. • Evidence that the Starter Pawl Repair Kit has been installed (holes in bottom of the flywheel below pawl pins).
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DISASSEMBLY, INSPECTION, & REPAIR ENGINE (cont.) Remove Spark Plug, Cylinder, and Piston Connecting Rod Assembly 1. Remove the spark plug from cylinder. Service the spark plug as instructed in Part 1 General Information. 2.6071.067 3 2. Remove the four (4) screws securing the crankcase cover to crankcase. Remove the crankcase cover and gasket. 2.6071.068 3. Remove the four (4) cylinder mounting screws. 2.6071.
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DISASSEMBLY, INSPECTION, & REPAIR ENGINE (cont.) 4. Remove the connecting rod from crankshaft. 5. Remove the cylinder with piston/connecting rod assembly from the crankcase as a unit. Remove the cylinder gasket. 2.6071.070 3 6. Remove the piston/connecting rod assembly from the cylinder. NOTE: Units with serial number 102084332 to 302010968 have one (1) piston ring. Units with serial number 302010969 and greater have two (2) piston rings. 2.6071.071 7. Remove the piston ring(s) from the piston.
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DISASSEMBLY, INSPECTION, & REPAIR ENGINE (cont.) Cylinder and Piston Inspection 1. Inspect the cylinder, piston, and piston ring(s) for wear and damage. Refer to the specifications and tolerances in Part 1 - General Information. Replace the cylinder, piston, or piston ring(s) if necessary. 2.6078.090 3 2. Install the piston ring(s) into the ring groove(s) in piston, and check the side clearance of piston ring(s). The maximum side clearance is 0.004 inch (0.101 mm).
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DISASSEMBLY, INSPECTION, & REPAIR ENGINE (cont.) 2. Remove the outer (sealed) bearing from the flywheel side of the crankcase using a bearing puller. 2.6071.075 3 3. Remove the inner (unsealed) bearing from the inside of the crankcase. 2.6071.076 Snap Rings 4. Remove the snap rings securing the inner seal in crankcase. 2.6071.
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DISASSEMBLY, INSPECTION, & REPAIR ENGINE (cont.) 5. Remove the inner seal from crankcase. 2.6071.078 3 Crankcase Inspection 1. Inspect the crankcase for nicks, cracks, and deformation. Replace if necessary. 2. Inspect the crankshaft for nicks, cracks, roundness, and deformation. Replace if necessary. 2.6071.076 Crankcase Reassembly NOTE: To prevent bearing damage, make sure bearings are fully supported on both the inner and outer races during all pressing operations.
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DISASSEMBLY, INSPECTION, & REPAIR ENGINE (cont.) 2. Make sure the race of the outer (sealed) bearing is packed with grease. If necessary, apply a small amount of a high quality grade 2 lithium based (or equivalent) bearing grease to the bearing. Keep the grease off of the inner and outer bearing surfaces that mate against the crankcase and crankshaft. Outer (Sealed) Bearing 3. Press the outer (sealed) bearing into the crankcase until it is flush with the crankcase surface.
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DISASSEMBLY, INSPECTION, & REPAIR ENGINE (cont.) Crankshaft/Bearing 8. Press the crankshaft/bearing assembly into the crankcase until the bearing is flush with the inner surface of the crankcase. 2.6071.082 3 9. Check the clearance between the inner surface of the crankcase and the crankshaft counterweight at several points. Recommended clearance is 0.030 in. (0.762 mm). Adjust the location of the crankshaft/bearing if necessary. 2.6071.
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REASSEMBLY General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Disassembly, Inspection, and Repair . . . . . . . . . . . . . . . . . . 3 Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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REASSEMBLY Table Of Contents Typical Assembly Sequence . . . . . . . . . . . . . . . . . . . . . . . . 4-3 Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4 Install Piston/Connecting Rod . . . . . . . . . . . . . . . . . . . . 4-4 Install Cylinder To Crankcase . . . . . . . . . . . . . . . . . . . . 4-5 Install Spark Plug . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6 Major Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7 Install Flywheel .
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REASSEMBLY Typical Disassembly Sequence The following sequence is suggested for complete engine REASSEMBLY. This procedure assumes that all components are new or have been reconditioned and all component subassembly work has been completed. This procedure can be varied to accommodate individual requirements for assembly and repair. 7. Install Clutch NOTE: Make sure the engine is assembled using all specified torque values and clearances.
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REASSEMBLY ENGINE Install Piston/Connecting Rod For units with one (1) piston ring, use the following instructions 1. If necessary, install the piston ring onto the piston. Make sure the ring end gap is located over the anti-rotation pin in the piston ring groove. 2.6071.072 4 2. Lubricate the piston and piston ring with 2-cycle engine oil. Compress the piston ring and insert the piston into the cylinder. 2.6071.071 3.
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REASSEMBLY ENGINE (cont.) For units with two (2) piston rings, use the following instructions. 1. If necessary, install the piston rings onto the piston. 2. Make sure the ring end gaps are located over the anti-rotation in the piston ring grooves. 2.6078.096 3. Lubricate the piston and piston rings with 2-cycle engine oil. Compress the piston rings and insert the piston into the cylinder.
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REASSEMBLY ENGINE (cont.) 4. Secure the crankcase to the cylinder with four (4) screws. Torque the screws to 50-60 in•lb (5.6-6.8 N•m). 2.6071.069 4 5. Install a new crankcase cover gasket, the crankcase cover, and attaching screws. Torque the screws to 55-65 in•lb (6.2-7.3 N•m). 2.6071.068 Install Spark Plug 1. Make sure the spark plug gap is set to 0.018-0.023 inch (0.045 to 0.058 mm) using a wire feeler gauge. 2. Install the spark plug into cylinder and torque to 100-120 in•lb (11.2-13.5 N•m). 2.
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REASSEMBLY MAJOR COMPONENTS Install Flywheel WARNING: Cracked or Broken Cooling Fins Are A Hazard! Be careful not to crank or break any cooling fins. They could fly off during operation. If cooling fins are cracked or broken, replace the flywheel. 1. Install the crankshaft key into the key way on crankshaft. 2.6071.066 2. Position the flywheel so that the key slot in the flywheel aligns with the crankshaft key. Place the flywheel onto the crankshaft. 2.6078.097 Install Ignition Module 1.
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REASSEMBLY MAJOR COMPONENTS (cont.) 2. Move the ignition module away from the flywheel as far as possible. Tighten the fastening screws slightly. 3. Insert a 0.010-0.015 in (0.254-0.381 mm) feeler gauge or shim stock between the ignition module and flywheel magnet surfaces. NOTE: Brass or plastic feeler gauge or shim stock is more suitable for this application because of the magnetic forces. 4. Loosen the module fastening screws and push the ignition module tight against the feeler gauge or shim stock. 2.
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REASSEMBLY MAJOR COMPONENTS (cont.) Install Clutch Standard N28 Engines 1. Install the spacer sleeve over the crankshaft. 2. Install the clutch rotor to the crankshaft. Make sure the side marked “OUT” is facing away from the starter housing. 2.6078.100 Clutch Tool 4 3. Install the flywheel holder, P/N 612470 or 180919. Using clutch tool, P/N 147337 or 180918, torque the clutch rotor to 150-160 in•lb (16.9-18 N•m). 4. Remove the flywheel holder. Flywheel Holder 2.6078.101 5.
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REASSEMBLY MAJOR COMPONENTS (cont.) Professional N28 Engines Clutch Tool 1. Install the spacer sleeve over the crankshaft. 2. Install the flywheel holder, P/N 612470. 3. Install the clutch rotor to crankshaft. 4. Using the TORO clutch tool for the professional N28 engine, torque the rotor to 130-150 in•lb (14.6-16.8 N•m). Flywheel Holder 2.6071.050 4 5. Install flat washer, clutch shoes, spring, and two (2) clutch shoe bolts. Torque the bolts to 60-80 in•lb (6.7-9 N•m). 2.6078.102 6.
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REASSEMBLY MAJOR COMPONENTS (cont.) Install Muffler 1. Install a new muffler gasket, muffler, and muffler mounting screws. Make sure the extended edge of the mufflercylinder gasket is between the muffler body and crankcase. Torque the muffler mounting screws to 80-90 in•lb (9.0-10.1 N•m). 2.6078.042 4 Install Carburetor Spacer 1. Insert the two (2) hex nuts into the pockets on the back of the carburetor spacer. 2.6078.104 2.
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REASSEMBLY MAJOR COMPONENTS (cont.) Install Heat Shield, Fuel Tank, and Bracket 1. Install the rubber fuel tank mounting pads to the fuel tank (on front and rear of the tank). 2. Place the heat shield over the muffler and hook into the crankcase. 2.6078.106 4 3. Install the fuel tank, fuel tank bracket, and two (2) attaching screws. Torque the screws to 50-60 in•lb (5.6-6.7 N•m). 2.6078.107 Install Rear Engine Cover 1. Install rear engine cover with two (2) screws.
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REASSEMBLY MAJOR COMPONENTS (cont.) Install Primer Bulb 1. Install primer bulb into air filter base. 2.6078.108 Install Carburetor, Choke, and Connect Fuel Lines To Carburetor Use the following procedures to install carburetor, fuel lines, and choke: NOTE: This unit has two fuel lines to the fuel tank. The clear line provides normal fuel flow. The blue line provides a return line for excess fuel flow during the primer operation.
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REASSEMBLY MAJOR COMPONENTS (cont.) Install Air Filter Make sure the air filter element is cleaned and oiled as instructed in Part 1 - General Information. CHOKE 1. Install the air filter element into the air filter cover. PARTIAL RUN 2. Install the air filter cover and attaching screws to air filter base. Torque the screws to 15-25 in•lb (1.7-2.8 N•m). 3.6069.004 Install Styling Cover 4 Units with professional N28 engines are equipped with an engine styling cover. To install the styling cover: 1.
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REASSEMBLY MAJOR COMPONENTS (cont.) 3. Install the anti-rotation screw through clamp and into boom. Torque the anti-rotation screw to 15-20 in•lb (1.7-2.3 N•m). Torque the nut and bolt of clamp to 70-80 in•lb (7.9-9 N•m). 3.6078.111 4 4. For units with serial number 102084332 to 302010968, install the throttle control cable and insert it through the hole in the swivel on carburetor throttle lever. Torque the screw in the swivel to 9-12 in•lb (1.0-1.4 N•m). 2.6071.015 5.
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REASSEMBLY MAJOR COMPONENTS (cont.) Professional N 28 Engines 1. Install the engine onto the trimmer drive housing. Make sure the drive shaft mates with the square drive of the engine. Make sure the slot in the flex drive housing aligns with the boss in the clutch housing/drum assembly. 2.6078.112 2. Install the anti-rotation screw through the clutch housing/drum assembly and into the boom. 4 Anti-Rotation Screw Torque the anti-rotation screw to 15-20 in•lb (1.7-2.3 N•m).
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REASSEMBLY MAJOR COMPONENTS (cont.) Prepare The Unit For Operation Before placing the unit back into service, be sure to do the following: • Make Sure all fasteners are tightened securely. • Fill the fuel tank with a fresh gasoline and 2-cycle oil mix. Refer to the “Fuel Recommendations” in Part 1 - General Information. • Adjust the carburetor high speed mixture, idle 2.6071.015 mixture, and idle speed settings. Refer to “Carburetor Adjustment” in Part 1 - General Information.
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