Yamaha YP250 Service Manual page 228

ELECTRICAL STARTING SYSTEM
YP803034
Inspection and repair
NOTE:
The mica insulation of the commutator must be
undercut to ensure proper operation of commu-
tator.
f: Continuity
Bad condition ! Replace.
8-20
1. Inspect:
S Commutator
Dirt ! Clean it with #600 grit sandpaper.
2. Measure:
S Commutator diameter a
Commutator wear limit:
27 mm
Out of specification ! Replace the starter
motor
3. Measure:
S Mica undercut a
Mica undercut:
0.7 mm
Out of specification ! Scrape the mica to
the proper value (a hacksaw blade can be
ground to fit).
4. Inspect:
S Armature coil resistances
(installation/continuity)
Defects ! Replace the starter motor.
If commutator is dirty, clean it with sandpa-
per.
Good
condition
f f
A
f
B
: No continuity
5. Measure:
S Brush length a
Out of specification ! Replace.
Brush length wear limit:
4.0 mm
6. Measure:
S Brush spring force
Fatigue/out of specification ! Replace as
a set.
ELEC
Bad condition
f