Poor Medium-And-High-Speed Performance; Faulty Gear Shifting; Shift Pedal Does Not Move; Jumps Out Of Gear - Yamaha RAPTOR YFM125RA Service Manual

2. Air filter
• Clogged air filter element
• Loosen air filter joint
Fuel system
1. Carburetor
• Faulty starter plunger
• Loose or clogged pilot jet
• Loose or clogged pilot air jet
• Damaged or loose carburetor joint
• Improperly adjusted engine idling speed
(throttle stop screw)
• Improper throttle lever free play
• Flooded carburetor
Electrical system
1. Battery
• Discharged battery
• Faulty battery
2. Spark plug
• Incorrect spark plug gap
• Incorrect spark plug heat range
• Fouled spark plug
• Worn or damaged electrode
• Worn or damaged insulator
• Faulty spark plug cap
3. Ignition coil
• Broken or shorted primary or secondary
coils
• Faulty spark plug lead
• Cracked or broken ignition coil
4. Ignition system
• Faulty CDI unit
• Faulty pickup coil
• Broken generator rotor woodruff key
EAS28510
POOR MEDIUM-AND-HIGH-SPEED PER-
FORMANCE
Refer to "STARTING FAILURES" on page 8-1.
Engine
1. Air filter
• Clogged air filter element
Fuel system
1. Carburetor
• Faulty diaphragm
• Incorrect fuel level
• Loose or clogged main jet
TROUBLESHOOTING
EAS28530

FAULTY GEAR SHIFTING

Shifting is difficult
Refer to "Clutch drags".
EAS28540

SHIFT PEDAL DOES NOT MOVE

Shift shaft
• Improperly adjusted shift rod
• Bent shift shaft
Shift drum and shift forks
• Foreign object in a shift drum groove
• Seized shift fork
• Bent shift fork guide bar
Transmission
• Seized transmission gear
• Foreign object between transmission gears
• Improperly assembled transmission
EAS28550

JUMPS OUT OF GEAR

Shift shaft
• Incorrect shift pedal position
• Improperly returned stopper lever
Shift forks
• Worn shift fork
Shift drum
• Incorrect axial play
• Worn shift drum groove
Transmission
• Worn gear dog
EAS28560

FAULTY CLUTCH

Clutch slips
1. Clutch
• Improperly assembled clutch
• Improperly adjusted clutch cable
• Loose or fatigued clutch spring
• Worn friction plate
• Worn clutch plate
2. Engine oil
• Incorrect oil level
• Incorrect oil viscosity (low)
• Deteriorated oil
Clutch drags
1. Clutch
• Unevenly tensioned clutch springs
8-2