Yamaha YZF-R125 Service Manual: Checking the starter motor

Yamaha YZF-R125 Service Manual / Engine / Electric starter / Checking the starter motor

1. Check:

  • Commutator Dirt Clean with 600 grit
    sandpaper.

2. Measure:

  • Commutator diameter "a" Out of specification Replace
    the starter motor.

Checking the starter motor


3. Measure:

  • Mica undercut "a" Out of specification Scrape
    the mica to the proper measurement with a hacksaw blade that has been grounded to fit the commutator.

NOTE:

The mica of the commutator must be undercut to ensure proper operation of the commutator.


4. Measure:

  • Armature assembly resistances (commutator and insulation) Out of specification Replace
    the starter motor.

a. Measure the armature assembly resistances with the pocket tester.


b. If any resistance is out of specification, replace the starter motor.

Checking the starter motor


5. Measure:

  • Brush length "a" Out of specification Replace
    the starter motor front cover/brush holder set.

Checking the starter motor


6. Measure:

  • Brush spring force Out of specification Replace
    the brush springs as a set.

7. Check:

Gear teeth Damage/wear  Replace the gear.


8. Check:

  • Bearing
  • Oil seal
  • Damage/wear Replace the
    starter motor front cover/brush holder set.
    Electric starter
    ...

    Assembling the starter motor
    1. Install: Starter motor front cover/brush holder set "1" Starter motor yoke "2" NOTE: Align the marks "a" on the starter motor yoke and starter motor front cover/brush holder set. ...

    Other materials:

    Faulty clutch
    Clutch slips 1. Clutch Improperly assembled clutch Improperly adjusted clutch cable Loose or fatigued clutch spring Worn friction plate Worn clutch plate 2. Engine oil Incorrect oil level Incorrect oil viscosity (low) Deteriorated oil Clutch drags 1. Clutch Unevenly t ...

    Bearings and oil seals
    Install bearings "1" and oil seals "2" so that the manufacturer's marks or numbers are visible. When installing oil seals "1", lubricate the oil seal lips with a light coat of lithium-soap-based grease. Oil bearings liberally when installing, if appropriate. CAUTION:Do not spin th ...

    Checking the camshaft
    1. Check: Camshaft lobes Blue discoloration/pitting/scratches  Replace the camshaft. 2. Measure: Camshaft lobe dimensions "a" and "b" Out of specification Replace the camshaft. 3. Check: Camshaft oil passage Obstruction Blow out with compressed air. ...

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