Checking The Starter Motor - Yamaha YZF-R125 Service Manual

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EAS24790

CHECKING THE STARTER MOTOR

1. Check:
• Commutator
Dirt → Clean with 600 grit sandpaper.
2. Measure:
• Commutator diameter "a"
Out of specification → Replace the starter
motor.
Limit
16.6 mm (0.65 in)
a
3. Measure:
• Mica undercut "a"
Out of specification → Scrape the mica to the
proper measurement with a hacksaw blade
that has been grounded to fit the commutator.
Mica undercut (depth)
1.35 mm (0.05 in)
NOTE:
The mica of the commutator must be undercut to
ensure proper operation of the commutator.
4. Measure:
• Armature assembly resistances (commutator
and insulation)
Out of specification → Replace the starter
motor.
M MMM M MMM M M MMM M
a. Measure the armature assembly resistances
with the pocket tester.
M MMM M M MMM M M MMM M
Armature coil
b. If any resistance is out of specification, re-
place the starter motor.
L LLL L LLL L
5. Measure:
• Brush length "a"
Out of specification → Replace the starter
motor front cover/brush holder set.
6. Measure:
• Brush spring force
Out of specification → Replace the brush
springs as a set.
MMM
5-36
ELECTRIC STARTER
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
Commutator resistance "1"
0.0315–0.0385 Ω
Insulation resistance "2"
Above 1 MΩ
L LLL L L LLL L L LLL L
Limit
3.50 mm (0.14 in)
Brush spring force
3.92–5.88 N (14.11–21.17 oz)
(400–600 gf)
L LLL L LLL