Yamaha RS90GTZ Service Manual page 385

ELECTRICAL STARTING SYSTEM
Inspection
1. Inspect:
NOTICE
Lightly grip the armature with a vise.
2. Measure:
3. Measure:
8-19
• Commutator (outer surface)
Dirty → Clean with #600 grit sandpaper
Hold the armature in a vise
or aluminium plate
• Commutator diameter
Measure the diameter
tor at points where the brush comes in con-
tact.
Out of specification → Replace the starter
motor.
Commutator diameter wear limit:
27.0 mm (1.06 in)
• Mica undercut (insulation depth)
(between commutator segments)
Out of specification → Scrape mica
proper limits.
Use a hacksaw blade
fit.
Mica undercut:
1.5 mm (0.06 in)
ELEC
.
and copper
.
of the commuta-
to
that is ground to