Yamaha WR450F, Owner'S Service Manual

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ELEC
ELECTRIC STARTING SYSTEM
INSPECTION AND REPAIR
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 which has been grounded to fit the
commutator.
NOTE:
The mica must be undercut to ensure proper
operation of the commutator.
Min. commutator diameter:
16.6 mm (0.65 in)
Mica undercut:
1.5 mm (0.06 in)
4. Measure:
• Armature assembly resistances (commu-
tator and insulation)
Out of specification
→
Replace the
starter motor.
• Measure the armature assembly resis-
tances with the pocket tester.
Pocket tester:
YU-03112-C/90890-03112
Armature assembly:
Commutator resistance
1
:
0.0117 ~ 0.0143
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.