10 - 2
TRBL
SHTG
STARTING FAILURE/HARD STARTING/POOR IDLE SPEED
PERFORMANCE/POOR MEDIUM AND HIGH-SPEED PERFORMANCE
COMPRESSION SYSTEM
Cylinder and cylinder head
●Loose spark plug
●Loose cylinder head or cylinder
●Broken cylinder head gasket
●Broken cylinder gasket
●Worn, damaged or seized cylinder
Piston and piston rings
●Improperly installed piston ring
●Worn, fatigued or broken piston ring
●Seized piston ring
●Seized or damaged piston
Valve, camshaft and crankshaft
●Improperly sealed valve
●Improperly contacted valve and valve seat
●Improper valve timing
●Broken valve spring
●Seized camshaft
●Seized crankshaft
POOR IDLE SPEED PERFORMANCEPOOR IDLE SPEED PERFORMANCE
Carburetor
●Improperly returned starter plunger
●Loose pilot jet
●Clogged pilot jet
●Clogged pilot air jet
●Improperly adjusted idle speed
(Throttle stop screw)
●Improper throttle cable play
●Flooded carburetor
Electrical system
●Faulty spark plug
●Faulty CDI unit
●Faulty pickup coil
●Faulty charging/rotor rotation direction coil
●Faulty ignition coil
Valve train
●Improperly adjusted valve clearance
Air filter
●Clogged air filter element
POOR MEDIUM AND HIGH-SPEED PERFORMANCEPOOR MEDIUM AND HIGH-SPEED PERFORMANCE
Refer to “STARTING FAILURE/HARD STARTING” and “POOR IDLE SPEED PERFORMANCE-
VALVE TRAIN”.
Carburetor
●Improper jet needle clip position
●Improperly adjusted fuel level
●Clogged or loose main jet
●Deteriorated or contaminated fuel
Air filter
●Clogged air filter element
10