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 InspectionMuffler Body Installation
Replace the muffler body gasket [A] with a new one.
Install the muffler body gasket to the premuffler chamber
[B] until it is bottomed so that the chamfer side faces premuffler
chamber.
Install the muffler body clamp [C] as shown in the figure.
Insert the projection [D] into the slot [ ...
Exploded View
AL: Tighten the two clamp bolts alternately two times to ensure even
tightening torque.
G: Apply grease.
R: Replacement Parts
G: Apply grease.
L: Apply a non-permanent locking agent.
R: Replacement Parts
Specifications
...
Tire 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 ...