Yamaha UMX - Shift Lever Does Not Move; Faulty Drive Train Performance; Overheating; Poor Braking Performance

TROUBLESHOOTING (YUM1A/YUM2A)
9-2
SHIFT LEVER DOES NOT MOVE
Shift shaft and shift forks
• Bent shift shaft
• Seized shift fork
Transmission
• Seized transmission gear
• Foreign object between transmission gears
• Improperly assembled transmission
FAULTY DRIVE TRAIN PERFORMANCE
Engine operates but vehicle will not move
1. V-belt
• Bent, damaged or worn V-belt
• Slipping V-belt
2. Primary sheave weight and primary sheave
slider
• Damaged or worn primary sheave weight
• Damaged or worn primary sheave slider
3. Transmission gear(s)
• Damaged transmission gear
Poor starting performance
1. V-belt
• V-belt slips
• Oil or grease on the V-belt
2. Primary and secondary sheaves
• Faulty operation
• Worn secondary sheave spring
Poor speed performance
1. V-belt
• Oil or grease on the V-belt
2. Primary sheave weight(s)
• Faulty operation
• Worn primary sheave weight
3. Primary fixed sheave
• Worn primary fixed sheave
4. Primary sliding sheave
• Worn primary sliding sheave
5. Secondary fixed sheave
• Worn secondary fixed sheave
6. Secondary sliding sheave
• Worn secondary sliding sheave
OVERHEATING
Engine
1. Clogged cooling air passages
2. Cylinder head and piston
• Heavy carbon buildup
3. Engine oil
• Incorrect oil level
• Incorrect oil viscosity
• Inferior oil quality
Cooling system
1. Cooling system
• Clogged engine cooling inlet duct
• Damaged flywheel fin
Fuel system
1. Throttle body
• Faulty throttle body
• Damaged or loose intake manifold
2. Air filter
• Clogged air filter element
Chassis
1. Brake(s)
• Dragging brake
Electrical system
1. Spark plug
• Incorrect spark plug gap
• Incorrect spark plug heat range
2. Ignition system
• Faulty ECU
POOR BRAKING PERFORMANCE
• Worn brake shoe
• Worn or rusty brake drum
• Incorrect brake pedal free play
• Incorrect brake shoe adjuster position
• Incorrect brake shoe position
• Damaged or fatigued brake shoe spring
• Oil or grease on the brake shoe
• Oil or grease on the brake drum
FAULTY SHOCK ABSORBER ASSEMBLY
Malfunction
• Fatigued or damaged shock absorber spring
• Bent or damaged damper rod
• Leaking oil
UNSTABLE HANDLING
1. Steering wheel
• Bent or improperly installed steering wheel
2. Steering components
• Incorrect toe-in
• Bent steering shaft
• Improperly installed steering shaft
• Damaged bearing