overheating YAMAHA YZ250F 2014 Owners Manual

9
TROUBLE SHOOTING
TROUBLE SHOOTING..................................................................................... 9-1
GENERAL INFORMATION ........................................................................ 9-1
STARTING FAILURES ............................................................................... 9-1
INCORRECT ENGINE IDLING SPEED ..................................................... 9-1
POOR MEDIUM-AND-HIGH-SPEED PERFORMANCE ............................ 9-2
FAULTY GEAR SHIFTING ......................................................................... 9-2
SHIFT PEDAL DOES NOT MOVE ............................................................. 9-2
JUMPS OUT OF GEAR.............................................................................. 9-2
FAULTY CLUTCH ...................................................................................... 9-2
OVERHEATING ......................................................................................... 9-2
OVERCOOLING ......................................................................................... 9-3
POOR BRAKING PERFORMANCE ........................................................... 9-3
FAULTY FRONT FORK LEGS ................................................................... 9-3
UNSTABLE HANDLING ............................................................................. 9-3
LIST OF SELF-DIAGNOSTIC AND FAIL-SAFE ACTIONS............................. 9-4

TROUBLE SHOOTING
9-2
3. Ignition system
• Faulty ECU
• Faulty crankshaft position sensor
• Broken generator rotor woodruff key
EAS1SM1354POOR MEDIUM-AND-HIGH-SPEED PER-
FORMANCE
Refer to “STARTING FAILURES” on page 9-1.
Engine
1. Air filter
• Clogged air filter element
Fuel system
1. Fuel pump
• Faulty fuel pump
2. Throttle body
• Defective throttle body
3. ECU
• Faulty ECU
EAS1SM1355FAULTY GEAR SHIFTING
Shifting is difficult
Refer to “CLUTCH” on page 5-35.
EAS1SM1356SHIFT PEDAL DOES NOT MOVE
Shift shaft
• 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
EAS1SM1357JUMPS 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
EAS1SM1358FAULTY CLUTCH
Clutch slips
1. Clutch
• Improperly assembled clutch
• Loose or fatigued clutch spring
• Worn friction plate
• Worn clutch plate
2. Engine oil
• Incorrect oil level
• Incorrect oil viscosity (low)
• Deteriorated oil
Clutch drags
1. Clutch
• Unevenly tensioned clutch springs
• Warped pressure plate
• Bent clutch plate
• Swollen friction plate
• Bent clutch push rod
• Damaged clutch boss
• Burnt primary driven gear bushing
2. Engine oil
• Incorrect oil level
• Incorrect oil viscosity (high)
• Deteriorated oil
EAS1SM1359OVERHEATING
Engine
1. Cylinder head and piston
• Heavy carbon buildup
• Clogged coolant passages
2. Engine oil
• Incorrect oil level
• Incorrect oil viscosity
• Inferior oil quality
Cooling system
1. Coolant
• Low coolant level
2. Radiator
• Damaged or leaking radiator
• Faulty radiator cap
• Bent or damaged radiator fin
3. Water pump
• Damaged or faulty water pump
• Damaged hose
• Improperly connected hose
• Damaged pipe
• Improperly connected pipe