CHECKING THE STARTER MOTOR

1. Check:
    • Commutator

       If dirty -> Clean with 600 grit sandpaper.

2. Measure:
    • Mica undercut "a"

      If out of specification -> Scrape the mica to the proper measurement with a hacksaw blade that has been
      grounded to fit the commutator.
Mica undercut (depth)
    0.70 mm (0.03 in)
The mica of the commutator must be undercut to ensure proper operation of the commutator.
3. Measure:
    • Armature assembly resistances (commutator and insulation)

      If out of specification -> Replace the starter motor.

      a. Measure the armature assembly resistances with the pocket tester.
Digital circuit tester
    90890-03174

Model 88 Multimeter with tachometer
    YU-A1927
Armature coil
    Commutator resistance "1"

    Continuity (0.0050-0.0150 ohms. at 20 °C (68 °F))

    Insulation resistance "2"

    No continuity (Above 1 Mohms at 20 °C (68 °F))
      b. If any resistance is out of specification, replace the starter motor.
4. Measure:
    • Brush length "a"

      If out of specification -> Replace the brush set assembly.
Brush overall length
    12.0 mm (0.47 in)

Limit
    6.50 mm (0.26 in)
5. Measure:
    Brush spring force

    If out of specification -> Replace the brush set assembly.
Brush spring force
6.025-6.515 N (614-664 gf, 21.69-23.45 oz)
6. Check:
    • Gear teeth

       If Damaged/Worn -> Replace the starter motor.

7. Check:
    • Bearing

      If Damaged/Worn -> Replace the starter motor.
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