- Commutator
Dirt → Clean with 600 grit sandpaper.
2. Measure:
- Commutator diameter «a»
Out of specification → Replace the starter motor.
Commutator wear limit: 27.0 mm (1.06 in).
![](https://motoinstruction.ru/img/yamaha/3/111876.jpg)
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: 0.7 mm (0.03 in).
Note: The mica of the commutator must be undercut to ensure proper operation of the commutator.
![](https://motoinstruction.ru/img/yamaha/3/111877.jpg)
4. Measure:
- Armature assembly resistances (commutator and insulation)
Out of specification → Replace the starter motor.
a. Measure the armature assembly resistances with the pocket tester.
Pocket tester: 90890-03112
Analog pocket tester: YU-03112-C
Armature coil:
- Commutator resistance «1»: 0.0250-0.0350 Ω at 20°C (68°F)
- Insulation resistance «2»: Above 1 МΩ at 20°C (68°F)
b. If any resistance is out of specification, replace the starter motor.
![](https://motoinstruction.ru/img/yamaha/3/111878.jpg)
5. Measure:
- Brush length «a»
Out of specification → Replace the brushes as a set.
Brush length wear limit: 5.0 mm (0.20 in).
![](https://motoinstruction.ru/img/yamaha/3/111879.jpg)
6. Measure:
- Brush spring force
Out of specification → Replace the brush springs as a set.
Brush spring force: 7.65-10.01 N (27.54-36.03 oz) (780-1021 gf)
![](https://motoinstruction.ru/img/yamaha/3/111880.jpg)
7. Check:
- Gear teeth
Damage/wear → Replace the gear.