Checking The Starter Motor - Yamaha 2009 YFM25RY Service Manual

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.
Commutator wear limit
21 mm (0.83 in)
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.
Mica undercut
1.5 mm (0.06 in)
TIP
The mica of the commutator must be undercut
to ensure proper operation of the commutator.
4. Measure:
• Armature assembly resistances (commu-
tator and insulation)
Out of specification → Replace the
starter motor.
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a. Measure the armature assembly resis-
tances with the pocket tester.
ELECTRIC STARTER
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
Armature coil
Commutator resistance "1"
0.013–0.015 Ω at 20 °C (68 °F)
Insulation resistance "2"
Above 1 MΩ at 20 °C (68 °F)
b. If any resistance is out of specification,
replace the starter motor.
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5. Measure:
• Brush length "a"
Out of specification → Replace the
brushes as a set.
Brush length wear limit
3.5 mm (0.14 in)
6. Measure:
• Brush spring force
Out of specification → Replace the brush
springs as a set.
Brush spring force
5.52–8.28
19.87–29.80 ozf)
5-51
N (563–844 gf,