Yamaha TT-R125EY Service Manual page 252

ELECTRIC STARTING SYSTEM
INSPECTION AND REPAIR
1. Inspect:
2. Measure:
3. Measure:
TIP
The mica insulation of the commutator must be
undercut to ensure proper operation of
commutator.
4. Measure:
6-13
• Commutator
Dirt → Clean it with #600 grit sandpaper.
• Commutator diameter a
Commutator wear limit:
21.0 mm (0.83 in)
Out of specification → Replace the starter
motor.
• Mica undercut a
Mica undercut:
1.5 mm (0.06 in)
Out of specification → Scrape the mica
to the proper value (a hacksaw blade can
be ground to fit).
• Armature assembly resistance (commuta-
tor 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
0.017 ~ 0.021 Ω at 20 °C (68 °F)
Insulation resistance 2
Above 1 MΩ at 20 °C (68 °F)
• If any resistance is out of specification,
replace the starter motor.
– +
ELEC