Yamaha TT-R90(V), Owner'S Service Manual, Page: 366 / 390

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– +
ELEC
INSPECTION AND REPAIR
1. Inspect:
• Commutator
Dirt
→
Clean it 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 value (a hacksaw blade can
be ground to fit).
NOTE:
The mica insulation of the commutator must be
undercut to ensure proper operation of com-
mutator.
Commutator wear limit:
16.6 mm (0.65 in)
Mica undercut:
1.35 mm (0.05 in)
4. Measure:
• Armature assembly resistance (commu-
tator and insulation)
Out of specification
→
Replace the
starter motor.
Measurement steps:
• Measure the armature assembly resis-
tances with the pocket tester.
Pocket tester:
YU-3112-C/90890-03112
Armature coil:
Commutator resistance
1
0.018 ~ 0.022
Ω
at 20 °C (68 °F)
Insulation resistance
2
Above 1 M
Ω
at 20 °C (68 °F)
• If any resistance is out of specification,
replace the starter motor.
ELECTRIC STARTING SYSTEM (TT-R90E)