Yamaha WR250FM Bicycle User Manual


 
6 - 14
+
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.
N
OTE:
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-3112-C/90890-03112
Armature assembly:
Commutator resistance
1
:
0.0189 ~ 0.0231
at 20 °C
(68 °F)
Insulation resistance
2
:
Above 1 M
at 20 °C (68 °F)
If any resistance is out of specification,
replace the starter motor.