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 InspectionTire Installation
WARNINGSome replacement tires may adversely
affect handling
and cause an accident resulting in serious injury
or death. To ensure proper handling and stability,
use only the recommended standard tires for
replacement, inflated to the standard pressure.
Inspect the rim ...
Special Tools
Bearing Puller:
57001-135
Head Pipe Outer Race Press Shaft:
57001-1075
Steering Stem Nut Wrench:
57001-1100
Bearing Driver Set:
57001-1129
Steering Stem Bearing Driver, 42.5:
57001-1344
Steering Stem Bearing Driver Adapter,
41.5:
57001-1345
Head Pipe Outer Race Driver, 55:
57001- ...
Drive Chain Lubrication Condition Inspection
If a special lubricant is not available, a heavy oil such as
SAE 90 is preferred to a lighter oil because it will stay on
the chain longer and provide better lubrication.
If the chain appears especially dirty, clean it before lubrication.
NOTICE
The O-rings between the side plates seal ...