Checking The Starter Motor - Yamaha MBK X-MAX 300 2017 Service Manual

EAS30325

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.
Commutator diameter
24.5 mm (0.96 in)
Limit
23.5 mm (0.93 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)
1.50 mm (0.06 in)
TIP
The mica of the commutator must be undercut to
ensure proper operation of the commutator.
4. Measure:
• Armature assembly resistance
Out of specification → Replace the starter
motor.
a. Measure the armature assembly resis-
tance with the digital circuit tester.
ELECTRIC STARTER
Digital circuit tester (CD732)
90890-03243
Model 88 Multimeter with ta-
chometer
YU-A1927
Armature coil resistance
0.063–0.077 Ω
1. Armature coil resistance
b. If the resistance is out of specification, re-
place the starter motor.
5. Measure:
• Brush length "a"
Out of specification → Replace the brushes
as a set.
Brush overall length
7.0 mm (0.28 in)
Limit
3.00 mm (0.12 in)
6. Measure:
• Brush spring force
Out of specification → Replace the brush
springs as a set.
Brush spring force
6.08–9.12 N (620–930 gf, 21.89–
32.83 oz)
5-54
1
a