Yamaha YB50 Service Manual page 160

INLET AND EXHAUST SYSTEM
FUEL TANK CAP
• Obstructed
FUEL PIPE
• Obstructed
MUFFLER
• Obstructed
EXHAUST PIPE
• Cracked or broken
• Carbon deposits
NEEDLE
• Badly adjusted
(Average speed)
AIR SCREW
• Badly adjusted
(Idling and starting)
ACCELERATOR STOPPING SCREW
• Badly adjusted
(Idling and starting)
PILOT JET
• Obstructed (Low range)
TROUBLE SHOOTING
FUEL COCK
• Obstructed
(CARBURETTOR)
8-3
DAMP TYPE
AIR FILTER ELEMENT
• Dirty or obstructed
CARBURETTOR JOINT
• Air leaks
MAIN JET
• Incorrect size
• Obstructed (High speed)
FLOAT VALVE
• Worn
FLOAT
• Incorrect adjustment of fuel level
• Broken
BOWL
• Accumulated dust and/or water
LOC
AVER