Yamaha WR250FM service manual Inspection and Repair, Min. commutator diameter 16.6 mm 0.65

ELECTRIC STARTING SYSTEM

ELEC

–+

INSPECTION AND REPAIR

1.Check:

•Commutator

Dirt → Clean with 600 grit sandpaper.

2.Measure:

•Commutator diameter a

Out of specification → Replace the starter motor.

Min. commutator diameter:

16.6mm (0.65 in)

3.Measure:

•Mica undercut a

Out of specification → Scrape the mica to the proper measurement with a hacksaw blade which has been grounded to fit the commutator.

Mica undercut: 1.5 mm (0.06 in)

NOTE:

The mica must be undercut to ensure proper operation of the commutator.

4.Measure:

•Armature assembly resistances (commu-

tator and insulation)

Out of specification → Replace the starter motor.

•Measure the armature assembly resis- tances with the pocket tester.

Pocket tester:

YU-3112-C/90890-03112

Armature assembly: Commutator resistance 1:

0.0189 ~ 0.0231 Ω at 20 °C

(68 °F)

Insulation resistance 2: Above 1 MΩ at 20 °C (68 °F)

•If any resistance is out of specification, replace the starter motor.

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