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:

    Checking the primary drive gear
    1. Remove: Primary drive gear Refer to "BALANCER GEAR" on page 5-53. 2. Check: Primary drive gear Damage/wear  Replace the primary drive gear and clutch housing as a set. Excessive noise during operation Replace the primary drive gear and clutch housing as a set ...

    Removing the piston
    1. Remove: Piston pin clips "1" Piston pin "2" Piston "3" CAUTION:Do not use a hammer to drive the piston pin out. NOTE: Before removing the piston pin clip, cover the crankcase opening with a clean rag to prevent the piston pin clip from falling in ...

    Specifications
    Dimensions: Overall length: 2015 mm (79.3 in) Overall width: 660 mm (26.0 in) Overall height: 1065 mm (41.9 in) Seat height: 818 mm (32.2 in) Wheelbase: 1355 mm (53.3 in) Ground clearance: 155 mm (6.10 in) Minimum turning radius: 3100 mm (122.0 in) Weight: With oil and fuel: 138.0 k ...

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