length YAMAHA WR 250F 2009 Owner's Manual

7-11
ELECTRIC STARTING SYSTEM
CHECKING AND REPAIRING THE
STARTER MOTOR
1. Check:• Commutator
Dirt →Clean with 600 grit sandpa-
per.
2. Measure:
• Commutator diameter "a"Out of specification →Replace the
starter motor.
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 commu-
tator.
The mica 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 pocket tester. b. If any resistance is out of specifi-
cation, replace the starter motor.
5. Measure:
• Brush length "a"Out of specification →Replace the
brushes as a set.
6. Measure: • Brush spring force
Out of specification →Replace the
brush springs as a set. ASSEMBLING THE STARTER
MOTOR
1. Install:
• Brush spring "1"
•Brush "2"
2. Install: • Armature assembly "1"
Install while holding down the
brush using a thin screw driver.
Be careful not to damage the brush
during installation.
3. Install:• Gasket "1"
• Starter motor yoke "2"
• Install the starter motor yoke with its groove "a" facing front cover.
• Align the match mark "b" on the starter motor yoke with the match
mark "c" on the starter motor rear
cover.
4. Install:• Gasket "1"
•Circlip
• Plain washer "2"
• Washer (starter motor front cover)
"3"
• Starter motor front cover "4"
Min. commutator diame-
ter:
16.6 mm (0.65 in)
Mica undercut: 1.5 mm (0.06 in)
Pocket tester: YU-3112-C/90890-
03112
Armature assembly:
Commutator resis-
tance "1":0.0189–0.0231 Ω at 20
°C (68 °F)
Insulation resistance
"2": Above 1 M Ωat 20 °C
(68 °F)
Min. brush length: 3.5 mm (0.14 in)
Brush spring force: 3.92–5.88 N (400–600
gf, 14.1–21.2 oz)