If any is worn down to the service limit, replace the brush assy.
Starter Motor Brush Length [B] Standard: 12.05 mm (0.4744 in.) Service Limit: 6.55 mm (0.258 in.)

Starter Motor Assembly
Commutator Cleaning and InspectionRadiator Cap Inspection
Remove:
Radiator Cap (see Coolant Change in the Periodic Maintenance
chapter)
Check the condition of the bottom [A] and top [B] valve
seals and valve spring [C].
If any one of them shows visible damage, replace the cap
with a new one.
Install the cap [A] on a cooling system pr ...
Gear Position Switch Installation
Securely place the springs [A] and pins [B] into the holes
[C] of the shift drum.
Apply grease to the new O-ring [D].
Install the gear position switch [E].
Apply a non-permanent locking agent to the threads of
the gear position switch screws [F].
Tighten:
Torque - Gear Position Swit ...
Idle Speed Inspection
Start the engine and warm it up thoroughly.
With the engine idling, turn the handlebar to both sides
[A].
If handlebar movement changes the idle speed, the
throttle cables may be improperly adjusted or incorrectly
routed, or damaged. Be sure to correct any of these
conditions before rid ...