Yamaha YFM25RSEY Automobile User Manual


 
TROUBLESHOOTING
8-2
EAS28490
INCORRECT ENGINE IDLING SPEED
Engine
1. Cylinder and cylinder head
Incorrect valve clearance
Damaged valve train components
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 cable 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
and “INCORRECT ENGINE IDLING SPEED”
on page 8-2.
Engine
1. Air filter
Clogged air filter element
Fuel system
1. Carburetor
Faulty diaphragm
Incorrect fuel level
Loose or clogged main jet
Improper jet needle clip position
Deteriorated or contaminated fuel
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
EAS28570
FAULTY CLUTCH
Clutch slips
1. Clutch
Improperly assembled clutch
Loose or fatigued clutch spring
Worn friction plate
Worn clutch plate
2. Engine oil