Yamaha XMAX YP125R - Service manual > Troubleshooting

General information


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 replacement of parts.

Starting failure/hard starting


1. Cylinder and cylinder head

2. Piston and piston ring(s)

3. Air filter

4. Crankcase and crankshaft

Fuel system

1. Fuel tank

2. Fuel pump

3. Throttle body

Electrical system

1. Battery

2. Fuse(s)

3. Spark plug

4. Ignition coil

5. Ignition system

6. Switches and wiring

7. Starting system

Incorrect engine idling speed


1. Cylinder and cylinder head

2. Air filter

Fuel system

1. Throttle body

Electrical system

1. Battery

2. Spark plug

3. Ignition coil

4. Ignition system

Poor medium-and-high-speed performance


1. Air filter

Fuel system

1. Fuel pump

Faulty clutch

Engine operates but vehicle will not move

1. V-belt

2. Primary pulley cam and primary pulley slider( s)

3. Transmission gear(s)

Clutch slips

1. Clutch shoe spring(s)

2. Clutch shoe(s)

3. Primary sliding sheave

Poor starting performance

1. V-belt

2. Primary sliding sheave

3. Clutch shoe(s)

Poor speed performance

1. V-belt

2. Primary pulley weight(s)

3. Primary fixed sheave

4. Primary sliding sheave

5. Secondary fixed sheave

6. Secondary sliding sheave



1. Clogged coolant passages

2. Engine oil

Cooling system

1. Coolant

2. Radiator

3. Water pump

4. Thermostat

5. Hose(s)

Fuel system

1. Throttle body

2. Air filter


1. Brake(s)

Electrical system

1. Spark plug

2. Ignition system


Cooling system

1. Thermostat

Poor braking performance

Faulty front fork legs

Leaking oil


Unstable handling

1. Handlebar

2. Steering head components

3. Front fork leg(s)

4. Swingarm

5. Rear shock absorber assembly(-ies)

6. Tire(s)

7. Wheel(s)

8. Frame

Faulty lighting or signaling system

Headlight does not come on

Headlight bulb burnt out

Tail/brake light does not come on

Tail/brake light bulb burnt out

Turn signal does not come on

Turn signals flash slowly

Turn signals remain lit

Turn signals flash quickly

Horn does not sound

Wiring diagram

YP125R/YP250R 2010

1. AC magneto

2. Crankshaft position sensor

3. Rectifier/regulator

4. Backup fuse (immobilizer unit and meter assembly)

5. Main switch

6. ECU fuse

7. Radiator fan motor fuse

8. Turn signal/hazard fuse

9. Ignition fuse

10.Headlight fuse

11. Signaling system fuse

12. Battery

13. Main fuse

14. Starter relay

15. Starter motor

16. Diode

17.Frame ground

18. Sidestand switch

19.Fuel pump

20. Starting circuit cut-off relay

21. Right handlebar switch

22. Start switch

23.Hazard switch

24. Front brake light switch

25.Coolant temperature sensor

26. Throttle position sensor

27. Intake air pressure sensor

28. Intake air temperature sensor

29.Lean angle sensor

30.Speed sensor

31.ECU (engine control unit)

32. Ignition coil

33.Spark plug

34.Fuel injector

35.O2 sensor

36. ISC (idle speed control) unit

37. Auxiliary DC jack (OPTION)


39. Turn signal/hazard relay

40.Headlight relay

41.Left handlebar switch

42. Dimmer switch

43.Pass switch

44. Turn signal switch

45.Horn switch

46. Rear brake light switch

47. Right tail/brake light assembly

48. Right rear turn signal light

49. Tail/brake light

50.Left tail/brake light assembly

51.Left rear turn signal light

52. Right front turn signal light

53.Left front turn signal light

54.Headlight assembly


56.Auxiliary light

57.License plate light

58.Fuel sender

59.V-belt replacement indicator reset coupler

60.Meter assembly

61. Immobilizer system indicator light

62.Multifunction meter



65.Engine oil change indicator

66.V-belt replacement indicator

67.Engine trouble warning light

68.Meter light

69.High beam indicator light

70.Right turn signal indicator light

71. Left turn signal indicator light

72.Air temperature sensor

73.Radiator fan motor

74.Radiator fan motor relay

75.Self-diagnosis signal coupler

76. Immobilizer unit

A. YP250R only


B- Black

Br- Brown

Ch- Chocolate

Dg- Dark green

G- Green

Gy- Gray

L- Blue

Lg- Light green

O- Orange

P- Pink

R- Red

Sb- Sky blue

W- White

Y- Yellow

B/L- Black/Blue

B/R- Black/Red

B/W- Black/White

Br/L- Brown/Blue

Br/R- Brown/Red

Br/W- Brown/White

G/B- Green/Black

G/L- Green/Blue

G/R- Green/Red

G/Y- Green/Yellow

Gy/B- Gray/Black

Gy/G- Gray/Green

Gy/R- Gray/Red

L/B- Blue/Black

L/R- Blue/Red

L/W- Blue/White

L/Y- Blue/Yellow

O/B- Orange/Black

O/R- Orange/Red

P/W- Pink/White

R/B- Red/Black

R/G- Red/Green

R/L- Red/Blue

R/W- Red/White

R/Y- Red/Yellow

W/B- White/Black

W/R- White/Red

W/Y- White/Yellow

Y/G- Yellow/Green

Y/L- Yellow/Blue

Wiring diagram

Wiring diagram

See also:

 Yamaha XMAX YP125R - Service manual > Checking the coolant temperature sensor

1. Remove: Coolant temperature sensor Refer to "CYLINDER HEAD (YP125R)" and "CYLINDER HEAD (YP250R)" WARNING Handle the coolant temperature sensor with special care. Never subject the coolant temperature sensor to strong shocks. If the coolant temperature sensor is dropped, replace it.

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