Incorrect Engine Idling Speed; Poor Medium-And-High-Speed Performance; Faulty Gear Shifting; Shift Pedal Does Not Move - Yamaha XG250 Service Manual

Faulty starter relay
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Faulty starting circuit cut-off relay
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Faulty starter clutch
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EAS28490

INCORRECT ENGINE IDLING SPEED

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

FAULTY GEAR SHIFTING

Shifting is difficult
Refer to "Clutch drags".
EAS28540

SHIFT PEDAL DOES NOT MOVE

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

JUMPS OUT OF GEAR

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

FAULTY CLUTCH

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