Checking The Starter Motor - Yamaha MTN1000 2016 Service Manual

EAS30325

CHECKING THE STARTER MOTOR

1. Check:
• Commutator
Dirt  Clean with 600 grit sandpaper.
2. 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.
Mica undercut (depth)
2.40 mm (0.09 in)
TIP
The mica of the commutator must be undercut to
ensure proper operation of the commutator.
3. Measure:
• Armature assembly resistances (commutator
and insulation)
Out of specification  Replace the starter
motor.
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a. Measure the armature assembly resistances
with the digital circuit tester.
Digital circuit tester
90890-03174
Model 88 Multimeter with tachom-
eter
YU-A1927
Armature coil resistance
0.0115–0.0140 
Insulation resistance
Above 1 M at 20 C (68 F)
b. If any resistance is out of specification, re-
place the starter motor.
ELECTRIC STARTER
1. Commutator resistance
2. Insulation resistance
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4. Measure:
• Brush length "a"
Out of specification  Replace the brush
holder set.
Brush overall length
11.0 mm (0.43 in)
Limit
5.50 mm (0.22 in)
5. Measure:
• Brush spring force
Out of specification  Replace the brush
holder set.
Brush spring force
4.80–7.20 N (489–734 gf, 17.28–
25.92 oz)
5-42
a