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 InspectionBrake Disc Warp Inspection
Raise the wheel off the ground with the jack.
Special Tools - Jack: 57001-1238
Jack Attachment: 57001-1608
For front disc inspection, turn the handlebar fully to one
side.
Set up a dial gauge against the disc [A] as shown in
the figure and measure disc runout, while turning [B] the
...
Air Cleaner Oil Draining
A drain hose is connected to the bottom of the air cleaner
to drain water or oil accumulated in the cleaner part.
Visually check the drain hose [A] if the water or oil accumulates.
If any water or oil accumulates in the hose, remove the
plug [B] from the drain hose and drain it.
...
Lighting System
This motorcycle adopt the daylight system and have a
headlight relay in the relay box. The headlight does not
go on when the ignition switch and the engine stop switch
are first turned on. The headlight comes on after the starter
button is released and stays on until the ignition switch is
turn ...