Faulty Gear Shifting - Yamaha TW125 1999 Service Manual

INCORRECT ENGINE IDLING SPEED/POOR MEDIUM AND-
HIGH-SPEED PERFORMANCE/FAULTY GEAR SHIFTING
EAS00846
INCORRECT ENGINE IDLING SPEED
ENGINE
Cylinders and cylinder head
S Incorrect valve clearance
S Damaged valve train components
Air filter
S Clogged air filter element
FUEL SYSTEM
Carburetor
S Faulty starter plunger
S Loose or clogged pilot jet
S Loose or clogged pilot air jet
S Damaged or loose carburetor joint
S Incorrectly adjusted engine idling speed
(throttle stop screw)
S Incorrect throttle cable free play
S Flooded carburetor
EAS00848
POOR MEDIUM-AND-HIGH-SPEED PERFORMANCE
Refer to "STARTING PROBLEMS".
ENGINE
Air filter
S Clogged air filter element
EAS00850

FAULTY GEAR SHIFTING

SHIFTING IS DIFFICULT
Refer to "CLUTCH DRAGS".
SHIFT PEDAL DOES NOT MOVE
Shift shaft
S Incorrectly adjusted shift rod
S Bent shift shaft
Shift drum and shift forks
S Foreign object in a shift drum groove
S Seized shift fork
S Bent shift fork guide bar
Transmission
S Seized transmission gear
S Foreign object between transmission gears
S Incorrectly assembled transmission
ELECTRICAL SYSTEMS
Battery
S Faulty battery
S Discharged battery
Spark plug
S Incorrect spark plug gap
S Incorrect spark plug heat range
S Fouled spark plug
S Worn or damaged electrode
S Worn or damaged insulator
S Faulty spark plug cap
Ignition coil
S Broken or shorted primary or secondary coils
S Faulty spark plug lead
S Damaged ignition coil
Ignition system
S Faulty CDI unit
S Faulty pickup coil
FUEL SYSTEM
Carburetors
S Faulty diaphragm
S Incorrect fuel level
S Loose or clogged main jet
JUMPS OUT OF GEAR
Shift shaft
S Incorrect shift pedal position
S Incorrectly returned stopper lever
Shift forks
S Worn shift fork
Shift drum
S Incorrect axial play
S Worn shift drum groove
Transmission
S Worn gear dog
8-2
TRBL
SHTG