Poor Idle Speed Performance; Poor Medium And High Speed Performance - Yamaha TTR250L Service Manual

STARTING FAILURE/HARD STARTING/POOR IDLE SPEED
PERFORMANCE/POOR MEDIUM AND HIGH SPEED PERFORMANCE
Switches and wiring
Faulty main switch
Faulty "ENGINE STOP" switch
Broken or shorted wiring
Faulty neutral switch
Faulty "START" switch
Faulty clutch switch
Piston and piston ring
Improperly installed piston ring
Worn, fatigued or broken piston ring
Seized piston ring
Seized or damaged piston

POOR IDLE SPEED PERFORMANCE

POOR IDLE SPEED PERFORMANCE
Carburetor
Improperly returned starter plunger
Loose pilot jet
Clogged pilot air jet
Improperly adjusted idle speed
(throttle stop screw/air screw)
Improper throttle cable free play
Flooded carburetor
NB292120

POOR MEDIUM AND HIGH SPEED PERFORMANCE

POOR MEDIUM AND HIGH SPEED PERFORMANCE
Refer to "Starting failure/Hard starting".
(FUEL SYSTEM, ELECTRICAL SYSTEM, COMPRESSION SYSTEM AND VALVE TRAIN)
Carburetor
Improper jet needle clip position
Diaphragm malfunction
Improperly adjusted fuel level
Clogged or loose main jet
Valve and camshaft
Improperly sealed valve
Improper valve to valve seat contact
Improper valve timing
Broken valve spring
Seized camshaft
Electrical system
Faulty battery
Faulty spark plug
Faulty CDI unit
Faulty pickup coil
Faulty ignition coil
Valve train
Improperly adjusted valve clearance
Air filter
Clogged air filter element
8 - 2
TRBL
SHTG
8