Yamaha UMAX, Service Manual

Page: 158 / 320

STARTER GENERATOR
5-19
CHECKING THE STARTER GENERATOR
1. Check:
• Commutator
Dirt
→
Clean with 600-grit sandpaper.
2. Measure:
• Commutator diameter “a”
Out of specification
→
Replace.
3. Measure:
• Mica undercut “a”
Out of specification
→
Cut the mica to the
proper measurement with a hacksaw blade
that has been grounded to fit the commutator.
TIP
The mica of the commutator must be undercut to
ensure proper operation of the commutator.
4. Measure:
• Armature assembly
a. Connect the digital circuit tester and check
the continuity.
b. If there is no continuity, replace the starter
generator.
5. Measure:
• Series field coil resistance
Out of specification
→
Replace the stator as-
sembly.
6. Measure:
• Shunt field coil resistance
Out of specification
→
Replace the stator as-
sembly.
7. Measure:
• Brush length “a”
Out of specification
→
Replace.
Commutator diameter limit
39 mm (1.54 in)
Mica undercut (depth)
0.70 mm (0.03 in)
Digital circuit tester (CD732)
90890-03243
Model 88 Multimeter with ta-
chometer
YU-A1927
a
Series field coil resistance
0.005–0.007
Ω
Shunt field coil resistance
4.5–5.5
Ω
Brush overall length limit
16 mm (0.63 in)
M
G R
G R