Yamaha YZF-R125 Service Manual: 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"
  • Negative tester probe
    black "2"

Checking the rectifier/regulator


c. Start the engine and let it run at approximately 5000 r/min.

d. Measure the charging voltage.

    Checking the stator coil
    1. Disconnect: Stator coil coupler (from the wire harness) 2. Check: Stator coil resistance Out of specification → Replace the crankshaft position sensor/stator assembly. a. Conne ...

    Checking the horn
    1. Check: Horn resistance Out of specification Replace. a. Disconnect the horn connectors from the horn terminals. b. Connect the pocket tester ( × 1) to the horn terminals. Positiv ...

    Other materials:

    Tachometer
    Tachometer Tachometer Tachometer red zone The electric tachometer allows the rider to monitor the engine speed and keep it within the ideal power range. When the key is turned to "ON", the tachometer needle will sweep once across the r/min range and then return to zero r/min ...

    Main switch/steering lock
    Main switch/steering lock The main switch/steering lock controls the ignition and lighting systems, and is used to lock the steering. The various positions are described below. ON All electrical circuits are supplied with power, the meter lighting, taillight, license plate light and ...

    Checking the front brake caliper
    1. Check: Brake caliper pistons "1" Rust/scratches/wear Replace the brake caliper assembly. Brake caliper body "2" Cracks/damage Replace the brake caliper assembly. Brake fluid delivery passages (brake caliper body) Obstruction Blow out with compressed air. ...

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