Checking The Starter Motor; Assembling The Starter Motor - Yamaha YZ450FN 2022 Owner's Service Manual

EAM30106

CHECKING THE STARTER MOTOR

1. Check:
• Commutator
Dirt  Clean with 600 grit sandpaper.
2. 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)
2.40 mm (0.09 in)
TIP
The mica of the commutator must be undercut to
ensure proper operation of the commutator.
3. Check:
• Armature assembly
a. Connect the digital circuit tester to the ar-
mature coil and check the continuity.
Digital circuit tester (CD732)
90890-03243
Model 88 Multimeter with tachom-
eter
YU-A1927
b. If there is no continuity, replace the starter
motor.
4. Measure:
• Brush length "a"
Out of specification  Replace the brush set.
ELECTRIC STARTER
Brush overall length limit
5.5 mm (0.22 in)
5. Measure:
• Brush spring force
Out of specification  Replace the brush set.
Brush spring force
4.80–7.20 N (489–734 gf, 17.28–
25.92 oz)
6. Check:
• Gear teeth
Damage/wear  Replace the starter motor.
7. Check:
• Oil seal
Damage/wear  Replace the defective
part(s).
EAM30107

ASSEMBLING THE STARTER MOTOR

1. Install:
• Brush spring "1"
• Brush "2"
TIP
Install the brush holder using the screws "a".
2
1
2. Install:
• Starter motor rear cover "1"
• O-ring
New
• Starter motor yoke "2"
TIP
Install the starter motor rear cover with its projec-
5-44
a
2
a