Yamaha XMAX YP125R - Service manual > Electric starter (YP250R)

Removing the starter motor

Disassembling the starter motor

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.

Limit 22.4 mm (0.88 in)

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) 1.00 mm (0.04 in)

TIP

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

4. Measure:

• Armature assembly resistances (commutator and insulation) Out of specification → Replace the starter motor.

a. Measure the armature assembly resistances with the digital circuit tester.

Digital circuit tester 90890-03174

Model 88 Multimeter with tachometer YU-A1927

Armature coil

Commutator resistance "1" Continuity (0.0100-0.0140 Ω at 20 ºC (68 ºF))

Insulation resistance "2" No continuity (Above 1 MΩ at 20 ºC (68 ºF))

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

5. Measure:

• Brush length "a"

Out of specification → Replace the brushes as a set.

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 7.75 N (790 gf, 27.90 oz)

7. Check:

• Gear teeth

Damage/wear → Replace the gear.

8. Check:

• Bearing

Damage/wear → Replace the bearing.

Assembling the starter motor

1. Install:

• Starter motor rear cover "1"
• Starter motor yoke "2"
• Starter motor front cover "3"

TIP

Align the match marks "a" on the starter motor yoke with the match marks "b" on the starter motor front and rear covers.

See also: