ELECTRIC STARTER
5-46
EAS24790
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.
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.
IP
The mica of the commutator must be undercut to
ensure proper operation of the commutator.
4. Measure:
• Armature assembly resistance (commutator
and insulation)
Out of specification → Replace the starter
motor.
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a. Measure the armature assembly resistance
with the digital circuit tester.
b. If any resistance is out of specification, re-
place the starter motor.
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5. Measure:
• Brush length “a”
Out of specification → Replace the brushes
as a set.
6. Measure:
• Brush spring force
Out of specification → Replace the brush
springs as a set.
Limit
27.0 mm (1.06 in)
Mica undercut (depth)
1.00 mm (0.04 in)
Digital circuit tester
90890-03174
Model 88 Multimeter with ta-
chometer
YU-A1927
Armature coil
Commutator resistance “1”
Continuity (0.0081–0.0099 Ω at
20 °C (68 °F))
Insulation resistance “2”
No continuity (Above 1 MΩ at 20
°C (68 °F))
Limit
7.60 mm (0.30 in)
Brush spring force
7.36–11.04 N (750–1126 gf,
26.49–39.74 oz)
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