General Information; Starting Failures; Incorrect Engine Idling Speed - Yamaha XT250X 2008 Service Manual

EAS28450
TROUBLESHOOTING
EAS28460

GENERAL INFORMATION

NOTE:
The following guide for troubleshooting does not
cover all the possible causes of trouble. It should
be helpful, however, as a guide to basic trouble-
shooting. Refer to the relative procedure in this
manual for checks, adjustments, and replace-
ment of parts.
EAS28470

STARTING FAILURES

Engine
1. Cylinder(s) and cylinder head(s)
Loose spark plug
G
Loose cylinder head or cylinder
G
Damaged cylinder head gasket
G
Damaged cylinder gasket
G
Worn or damaged cylinder
G
Incorrect valve clearance
G
Improperly sealed valve
G
Incorrect valve-to-valve-seat contact
G
Incorrect valve timing
G
Faulty valve spring
G
Seized valve
G
2. Piston(s) and piston ring(s)
Improperly installed piston ring
G
Damaged, worn or fatigued piston ring
G
Seized piston ring
G
Seized or damaged piston
G
3. Air filter
Improperly installed air filter
G
Clogged air filter element
G
4. Crankcase and crankshaft
Improperly assembled crankcase
G
Seized crankshaft
G
Fuel system
1. Fuel tank
Empty fuel tank
G
Clogged fuel filter
G
Clogged fuel strainer
G
Clogged fuel tank drain hose
G
Clogged rollover valve
G
Clogged rollover valve hose
G
Deteriorated or contaminated fuel
G
2. Fuel pump
Faulty fuel pump
G
Faulty fuel pump relay
G
3. Fuel cock
Clogged or damaged fuel hose
G
4. Carburetor(s)
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8-1
TROUBLESHOOTING
Deteriorated or contaminated fuel
G
Clogged pilot jet
G
Clogged pilot air passage
G
Sucked-in air
G
Damaged float
G
Worn needle valve
G
Improperly installed needle valve seat
G
Incorrect fuel level
G
Improperly installed pilot jet
G
Clogged starter jet
G
Faulty starter plunger
G
Improperly adjusted starter cable
G
Electrical system
1. Battery
Discharged battery
G
Faulty battery
G
2. Fuse(s)
Blown, damaged or incorrect fuse
G
Improperly installed fuse
G
3. Spark plug(s)
Incorrect spark plug gap
G
Incorrect spark plug heat range
G
Fouled spark plug
G
Worn or damaged electrode
G
Worn or damaged insulator
G
Faulty spark plug cap
G
4. Ignition coil(s)
Cracked or broken ignition coil body
G
Broken or shorted primary or secondary coils
G
Faulty spark plug lead
G
5. Ignition system
Faulty ignitor unit
G
Faulty pickup coil
G
Broken generator rotor woodruff key
G
6. Switches and wiring
Faulty main switch
G
Faulty engine stop switch
G
Broken or shorted wiring
G
Faulty neutral switch
G
Faulty start switch
G
Faulty sidestand switch
G
Faulty clutch switch
G
Improperly grounded circuit
G
Loose connections
G
7. Starting system
Faulty starter motor
G
Faulty starter relay
G
Faulty starting circuit cut-off relay
G
Faulty starter clutch
G
EAS28490

INCORRECT ENGINE IDLING SPEED

Engine
1. Cylinder(s) and cylinder head(s)