User Guide

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5. FUEL SYSTEM

5-0

MX’er 50

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FUEL SYSTEM

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SERVICE INFORMATION -------------------------------------------- 5- 2

TROUBLESHOOTING ------------------------------------------------- 5- 2

THROTTLE VALVE DISASSEMBLY/CARBURETOR REMOVAL- 5- 3

AUTO BYSTARTER---------------------------------------------------- 5- 6

FLOAT/FLOAT VALVE/JETS ---------------------------------------- 5- 8

CARURETOR INSTALLATION -------------------------------------- 5-11

AIR SCREW ADJUSTMENT ------------------------------------------ 5-12

REED VALVE----------------------------------------------------------- 5-13

FUEL TANK------------------------------------------------------------- 5-14

FUEL VALVE REMOVAL -------------------------------------------- 5-15

AIR CLEANER ---------------------------------------------------------- 5-15

Summary of content (16 pages)

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5. FUEL SYSTEM MX’er 50 SERVICE INFORMATION GENERAL INSTRUCTIONS • When working with gasoline, keep away from sparks and flames.. • Note the locations of O-rings when disassembling and replace them with new ones during assembly. • All cables, fuel lines and wires must be routed and secured at correct locations. • Bleed air from the oil lines whenever they are disconnected. SPECIFICATIONS MX’er 50 14mm PB 16.3mm #78 #40 2±_ 2000±100rpm 1_ 4mm Venturi dia.
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5. FUEL SYSTEM MX’er 50 Carburetor Cap THROTTLE VALVE DISASSEMBLY/CARBURETOR REMOVAL Loosen the carburetor cap and remove the throttle valve. Disconnect the throttle cable from the throttle valve. Throttle Valve Carburetor Cap Remove the throttle valve spring, carburetor cap and rubber seal.
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. FUEL SYSTEM MX’er 50 Remove the jet needle by removing the needle clip. Check the jet needle and throttle valve for wear or damage. Needle Clip Jet Needle Needle Retainer 2nd Notch (STD) Throttle Valve Carburetor Cap Rubber Seal THROTTLE VALVE INSTALLA-TION Install the jet needle on the throttle valve and secure with the needle clip. Install the rubber seal on the throttle cable and then install the carburetor cap and throttle valve spring.
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5. FUEL SYSTEM Install the throttle valve by aligning the groove in the throttle valve with the throttle stop screw. Tighten the carburetor cap. After installation, perform the following adjustments and inspections. • Throttle cable free play (!3-3) • Idle speed adjustment (!3-7) Install the met-in box. CARBURETOR REMOVAL Remove the air cleaner by removing the air cleaner band screw and attaching bolts. Disconnect the fuel tube. Loosen the drain bolt to drain fuel from the carburetor.
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5. FUEL SYSTEM MX’er 50 Remove the two carburetor lock nuts. Remove the carburetor. Nuts AUTO BYSTARTER AUTO BYSTARTER INSPECTION Measure the resistance between the auto bystarter wire terminals. Resistance: 5W (10 minutes minimum after stopping the engine) If the resistance exceeds 5W, replace the auto bystarter with a new one. After the engine stops for 30 minutes, connect a hose to the fuel enriching circuit and blow the hose with mouth.
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5. FUEL SYSTEM MX’er 50 Connect the auto bystarter yellow wire to the battery positive (+) terminal and green/ black wire to the battery negative (-) terminal and wait 5 minutes. Connect a hose to the fuel enriching circuit and blow the hose with mouth. If air can be blown into the hose, the auto bystarter is faulty and replace it with a new one. Auto Bystarter AUTO BYSTARTER REMOVAL Remove the auto bystarter cover. Remove the two auto bystarter set plate screws to remove the auto bystarter.
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5. FUEL SYSTEM AUTO BYSTARTER INSTALLATION Install the auto bystarter into the carburetor body until it bottoms.. Install the set plate and then tighten the two screws. MX’er 50 Screws Auto Bystarter Set Plate FLOAT/FLOAT VALVE/JETS FLOAT CHAMBER Remove the two float chamber screws and the float chamber. Screws Remove the screw and O-ring. Remove the float pin, float and float valve.
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5. FUEL SYSTEM FLOAT/FLOAT VALVE INSPECTION Inspect the float for damage or fuel inside the float. Check the float valve seat for wear or damage. MX’er 50 Float Valve Float Seat Main Jet JETS/SCREWS REMOVAL Before removing the throttle stop screw or air screw, record the number of rotations until it seats lightly. Then, remove them. °ØDo not force the air screw against its seat to prevent damage. Remove the main jet and needle jet holder.
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5. FUEL SYSTEM FLOAT CHAMBER ASSEMBLY Install the main jet and needle jet holder. Install the air screw and throttle stop screw according to the rotations recorded. MX’er 50 Main Jet Needle Jet holder °ØIf the air screw must be replaced, be sure to perform the air screw adjustment again. Throttle Stop Screw Install the float valve, float and float pin. Tighten the float screw securely.
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5. FUEL SYSTEM MX’er 50 O-rings CARBURETOR INSTALLATION °ØWhen installation, do not allow foreign particles to enter the carburetor. Check the carburetor insulator and O-ring for wear or damage. Insulator Install the carburetor and insulator onto the intake manifold and tighten the two lock nuts. Connect the fuel tube and auto bystarter wire connector. °ØRoute the auto bystarter wire correctly and properly. Nuts Carburetor Cap Fuel Tube Install the carburetor cap.
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5. FUEL SYSTEM AIR SCREW ADJUSTMENT MX’er 50 Air Screw Turn the air screw clockwise until it seats lightly and back it to the specification given. °ØDo not force the air screw against its seat to prevent damage. Start the engine and turn the air screw in or out slowly to obtain the highest engine speed. Throttle Stop Screw Turn the throttle stop screw to obtain the specified idle speed.
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5. FUEL SYSTEM REED VALVE MX’er 50 Bolts REMOVAL Remove the four intake manifold bolts and gasket. Remove the reed valve and gasket. Intake Manifold INSPECTION Check the reed valve for damaged or weak reeds. Check the reed valve seat for cracks, damage or clearance between the seat and reed. Replace the valve if necessary. Reeds Reed Stopper °Ø Do not disassemble or bend the reed stopper. To do so can cause loss of engine power and engine damage.
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5. FUEL SYSTEM FUEL TANK MX’er 50 Lever Seat FUEL TANK REMOVAL Warning • Keep sparks and flames away from the work area. • Wipe off any spilled gasoline. Remove the seat. Remove the center cover. Remove the right and left front fender. Screws Bolts Remove two bolts on the end of the fuel tank. Center Cover Fuel Tank Fuel Tubes Switch the fuel valve “OFF”. Disconnect the fuel tubes. Remove the fuel tank and fuel valve.
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5. FUEL SYSTEM MX’er 50 Fuel Tubes FUEL VALVE REMOVAL Disconnect the fuel tubes and remove the bolts. Fuel Valve Remove the fuel valve and fuel cup. Remove the screw on the fuel valve control switch. Remove the two screws on the fuel valve body. Fuel Valve Fuel Valve Body Washer Control Switch INSPECTION Inspect the fuel valve strainer for dirt and clog. Clean if necessary. Replace the O-rings with new ones if they are damaged or deteriorated.