Chapter 8. Troubleshooting; Starting Failure/Hard Starting; Fuel System; Electrical System - Yamaha CW50L Service Manual

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- 8 I STARTING FAILURE/HARD STARTING/ TRBL ep I
STARTING FAILURE/HARD STARTING
SHTG _
POOR IDLE SPEED PERFORMANCE
SHTG
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TROUBLESHOOTING
COMPRESSION SYSTEM
Cylinder and cylinder head Crankcase and crankshaft
NOTE: • Loose spark plug • Improperly seated crankcase
The following troubleshooting does not cover all the possible causes of trouble. It should be helpful, • Loose cylinder head or cylinder • Improperly sealed crankcase
however, as a guide to troubleshooting. Refer to the relative procedure in this manual for inspection, - Broken cylinder head gasket (damaged oil seal)
adjustment and replacement of parts. • Broken cylinder gasket • Seized crankshaft
• Worn, damaged or seized cylinder Reed valve
STARTING FAILURE/HARD STARTING
Piston and piston rings • Deformed reed valve stopper
FUEL SYSTEM • Improperly installed piston ring • Improperly seated reed valve
Fuel tank Carburetor • Worn, fatigued or broken piston ring • Loose intake manifold
• Empty • Deteriorated fuel, fuel containing, water or o Seized piston ring • Broken gasket
• Clogged fuel filter foreign material • Seized or damaged piston • Broken reed valve
• Deteriorated fuel or fuel containing water or - Clogged pilot jet
foreign material • Clogged pilot air passage
• Clogged fuel tank cap • Sucked-in air
Fuel cock • Deformed float
• Clogged fuel hose • Groove-worm needle valve
Air cleaner • Improperly sealed valve seat POOR IDLE SPEED
PERFORMANCE
• Clogged air filter • Improperly adjusted fuel level POOR IDLE SPEED PERFORMANCE
• Improperly set pilot jet Carburetor
• Clogged starter jet o Improperly returned starter plunger
• Starter plunger malfunction ° Clogged or loose pilot jet
• Improperly adjusted pilot air screw • Clogged pilot air jet
• Improperly adjusted idle speed ( throttle stop screw)
• Improper throttle cable play
ELECTRICAL SYSTEM ° Flooded c arburetor
Sparkplug CDIunitsystem
° Improper plug gap ° Faulty CDI unit
• Worm electrodes ° Faulty source coil
• Wire between terminals broken • Faulty pick-up coil
• Improper heat range Switches and wiring
° Faulty spark plug cap • Faulty main switch
Ignition coil • Broken or shorted wiring
• Broken or shorted primary/secondary • Faulty" ENGINE STOP" switch
• Faulty spark plug lead
• Broken body
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