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TROUBLESHOOTING
9-1
EAS1SM9348
TROUBLESHOOTING
EAS1SM9349
GENERAL INFORMATION
TIP
The following guide for troubleshooting does
not cover all the possible causes of trouble. It
should be helpful, however, as a guide to basic
troubleshooting. Refer to the relative procedure
in this manual for checks, adjustments, and re-
placement of parts.
EAS1SM9350
STARTING FAILURES
Engine
1. Cylinder and cylinder head
• Loose spark plug
• Loose cylinder head or cylinder
• Damaged cylinder head gasket
• Damaged cylinder gasket
• Worn or damaged cylinder
• Incorrect valve clearance
• Improperly sealed valve
• Incorrect valve-to-valve-seat contact
• Incorrect valve timing
• Faulty valve spring
• Seized valve
2. Piston and piston ring(s)
• Improperly installed piston ring
• Damaged, worn or fatigued piston ring
• Seized piston ring
• Seized or damaged piston
3. Air filter
• Improperly installed air filter
• Clogged air filter element
4. Crankcase and crankshaft
• Improperly assembled crankcase
• Seized crankshaft
Fuel system
1. Fuel tank
• Empty fuel tank
• Clogged fuel tank breather hose
• Deteriorated or contaminated fuel
• Clogged or damaged fuel hose
2. Fuel pump
• Faulty fuel pump
3. Throttle body
• Deteriorated or contaminated fuel
• Sucked-in air
Electrical system
1. Spark plug
• Incorrect spark plug gap
• Incorrect spark plug heat range
• Fouled spark plug
• Worn or damaged electrode
• Worn or damaged insulator
2. Ignition coil
• Cracked or broken ignition coil body
• Broken or shorted primary or secondary
coils
3. Ignition system
• Faulty ECU
• Faulty crankshaft position sensor
• Broken generator rotor woodruff key
4. Switches and wiring
• Faulty ECU
• Faulty engine stop switch
• Broken or shorted wiring
• Faulty neutral switch
• Improperly grounded circuit
• Loose connections
EAS1SM9351
INCORRECT ENGINE IDLING SPEED
Engine
1. Cylinder and cylinder head
• Incorrect valve clearance
• Damaged valve train components
2. Air filter
• Clogged air filter element
Fuel system
1. Throttle body
• Damaged or loose throttle body joint
• Improperly synchronized throttle bodies
• Improper throttle cable free play
• Flooded throttle body
Electrical system
1. 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
2. Ignition coil
• Broken or shorted primary or secondary
coils
• Cracked or broken ignition coil
Summary of Contents for YZ250F 2016
Page 4: ......
Page 10: ......
Page 12: ......
Page 16: ...LOCATION OF IMPORTANT LABELS 1 2 EUR ...
Page 17: ...LOCATION OF IMPORTANT LABELS 1 3 AUS NZL ZAF ...
Page 40: ...CLEANING AND STORAGE 1 26 ...
Page 63: ...LUBRICATION POINTS AND LUBRICANT TYPES 2 22 ...
Page 66: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 2 25 ...
Page 68: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 2 27 ...
Page 70: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 2 29 ...
Page 72: ...CABLE ROUTING DIAGRAM 2 31 EAS1SM9062 CABLE ROUTING DIAGRAM ...
Page 74: ...CABLE ROUTING DIAGRAM 2 33 ...
Page 76: ...CABLE ROUTING DIAGRAM 2 35 ...
Page 78: ...CABLE ROUTING DIAGRAM 2 37 ...
Page 80: ...CABLE ROUTING DIAGRAM 2 39 ...
Page 82: ...CABLE ROUTING DIAGRAM 2 41 ...
Page 122: ...ELECTRICAL SYSTEM 3 38 ...
Page 190: ...CHAIN DRIVE 4 66 ...
Page 286: ......
Page 293: ...CHARGING SYSTEM 8 7 2 AC magneto 3 Rectifier regulator 4 Joint connector 5 Condenser ...
Page 295: ...CHARGING SYSTEM 8 9 ...
Page 321: ...FUEL PUMP SYSTEM 8 35 ...
Page 322: ...ELECTRICAL COMPONENTS 8 36 EAS1SM9331 ELECTRICAL COMPONENTS EAS1SM9332 9 10 1 2 3 4 5 6 7 8 ...
Page 324: ...ELECTRICAL COMPONENTS 8 38 EAS1SM9333 CHECKING THE SWITCHES Y W P Sb 1 2 P Sb Y W ...
Page 325: ...ELECTRICAL COMPONENTS 8 39 1 Engine stop switch 2 Neutral switch ...
Page 334: ...ELECTRICAL COMPONENTS 8 48 ...
Page 342: ...LIST OF SELF DIAGNOSTIC AND FAIL SAFE ACTIONS 9 7 ...
Page 353: ......
Page 354: ...PRINTED IN JAPAN E PRINTED ON RECYCLED PAPER ...