TROUBLESHOOTING
9-2
• 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
• Faulty spark plug lead
4. Ignition system
• Faulty ECU
• Faulty crankshaft position sensor
EAS28510
POOR MEDIUM-AND-HIGH-SPEED
PERFORMANCE
Refer to “STARTING FAILURE/HARD START-
ING” on page 9-1.
Engine
1. Air filter
• Clogged air filter element
Fuel system
1. Fuel pump
• Faulty fuel pump
EAS28580
FAULTY CLUTCH
Engine operates but vehicle will not move
1. V-belt
• Bent, damaged or worn V-belt
• Slipping V-belt
2. Primary pulley cam and primary pulley slid-
er(s)
• Damaged or worn primary pulley cam
• Damaged or worn primary pulley slider
3. Transmission gear(s)
• Damaged transmission gear
Clutch slips
1. Clutch shoe spring(s)
• Damaged, loose or worn clutch shoe spring
2. Clutch shoe(s)
• Damaged or worn clutch shoe
3. Primary sliding sheave
• Seized primary sliding sheave
Poor starting performance
1. V-belt
• V-belt slips
• Oil or grease on the V-belt
2. Primary sliding sheave
• Faulty operation
3. Clutch shoe(s)
• Bent, damaged or worn clutch shoe
Poor speed performance
1. V-belt
• Oil or grease on the V-belt
2. Primary pulley weight(s)
• Faulty operation
• Worn primary pulley weight
3. Primary fixed sheave
• Worn primary fixed sheave
4. Primary sliding sheave
• Worn primary sliding sheave
5. Secondary fixed sheave
• Worn secondary fixed sheave
6. Secondary sliding sheave
• Worn secondary sliding sheave
EAS28600
OVERHEATING
Engine
1. Clogged coolant passages
• Cylinder head and piston
• Heavy carbon buildup
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
4. Thermostat
• Thermostat stays closed
5. Hose(s)
• Damaged hose
• Improperly connected hose
Fuel system
1. Throttle body
• Damaged or loose throttle body joint
2. Air filter
• Clogged air filter element
Summary of Contents for YP125R
Page 1: ...SERVICE MANUAL 2010 37P F8197 E0 YP125R YP250R...
Page 6: ......
Page 8: ......
Page 28: ...SPECIAL TOOLS 1 19...
Page 30: ...COOLING SYSTEM DIAGRAMS YP250R 2 73 CABLE ROUTING YP250R 2 75...
Page 31: ......
Page 55: ...LUBRICATION POINTS AND LUBRICANT TYPES YP125R 2 24...
Page 62: ...CABLE ROUTING YP125R 2 31 Front fork front view A 1 1 1 1 2 2 2 3 4 5 6 7...
Page 66: ...CABLE ROUTING YP125R 2 35 Engine right side view A 7 3 2 2 2 1 3 4 5 6 7...
Page 70: ...CABLE ROUTING YP125R 2 39 Engine left side view 2 1 3 4 A 3...
Page 72: ...CABLE ROUTING YP125R 2 41 Handlebar top view A 1 2 3 4 4 5 6 7 8 9 10 11 12 13 14 15 16 17...
Page 76: ...CABLE ROUTING YP125R 2 45 Tail brake light top view 2 1 3 4 B A 1 5 6...
Page 103: ...LUBRICATION POINTS AND LUBRICANT TYPES YP250R 2 72...
Page 108: ...CABLE ROUTING YP250R 2 77 Front fork front view 1 1 2 3 4 5 6 7 1 2 A 1 2...
Page 112: ...CABLE ROUTING YP250R 2 81 Engine right side view A 7 3 2 2 2 1 3 4 5 6 7 8 B...
Page 116: ...CABLE ROUTING YP250R 2 85 Engine left side view 2 1 3 4 5 6 B A 3 7...
Page 118: ...CABLE ROUTING YP250R 2 87 Handlebar top view A 1 2 3 4 4 5 6 7 8 8 9 10 11 12 13 14 15 16 17...
Page 122: ...CABLE ROUTING YP250R 2 91 Tail brake light top view 2 1 3 4 B A 1 5 6 8 7...
Page 124: ...CABLE ROUTING YP250R 2 93...
Page 127: ......
Page 172: ...ELECTRICAL SYSTEM 3 45...
Page 175: ......
Page 240: ...REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM 4 65...
Page 245: ......
Page 305: ...CRANKSHAFT YP125R 5 60 a 1...
Page 366: ...CRANKSHAFT YP250R 5 121...
Page 394: ...THROTTLE BODY 7 11...
Page 397: ......
Page 411: ...CHARGING SYSTEM 8 14...
Page 423: ...SIGNALING SYSTEM 8 26...
Page 427: ...COOLING SYSTEM 8 30...
Page 453: ...FUEL INJECTION SYSTEM 8 56...
Page 457: ...FUEL PUMP SYSTEM 8 60...
Page 466: ...IMMOBILIZER SYSTEM 8 69 a Light on b Light off...
Page 467: ...IMMOBILIZER SYSTEM 8 70...
Page 495: ......
Page 496: ...YAMAHA MOTOR ESPA A S A...