Yamaha YZF-R125 Service Manual: Troubleshooting

The ignition system fails to operate (no spark or intermittent spark).

NOTE:

  • Before troubleshooting, remove the following part(s):

1. Seats

2. Fuel tank

3. Right side cover

4. Left side panel

5. Left upper side cowling

Troubleshooting


Troubleshooting


    Circuit diagram
    2. Crankshaft position sensor 4. Main fuse 5. Main switch 8. Sidestand switch 9. Battery 17.Engine stop switch 23.Lean angle sensor 25.ECU (engine control unit) 26.Ignition coil 27.Spark ...

    Electric starting system
    ...

    Other materials:

    Checking the rectifier/regulator
    1. Check: Rectifier/regulator output voltage Out of specification → Replace the rectifier/ regulator. a. Set the engine tachometer to the spark plug lead. b. Connect the pocket tester (DC 20 V) to the rectifier/regulator coupler as shown. Positive tester probe red "1" Negat ...

    Checking the coolant temperature sensor
    1. Remove: Coolant temperature sensor 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. 2. Check: Coolant temper ...

    Installing the exhaust assembly
    1. Install: Exhaust assembly "1" Exhaust pipe nuts "2" Exhaust assembly bolts "3" "4" NOTE: Do not fully tighten the nuts and bolts. 2. Tighten: Exhaust pipe nuts "2" Exhaust assembly bolt "4" Exhaust assembly bolt "3" ...

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