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 InspectionTachometer
The tachometer shows the engine
speed in revolutions per minute (r/min,
rpm).
On the right side of the tachometer
face is a portion called the “red zone”.
Engine r/min (rpm) in the red zone is
above maximum recommended engine
speed and is also above the range for
good performance.
...
Crankcase Assembly
NOTICE
The upper and lower crankcase halves are machined
at the factory in the assembled state, so the
crankcase halves must be replaced as a set.
With a high flash-point solvent, clean off the mating surfaces
of the crankcase halves and wipe dry
WARNINGGasoline and low flash-poin ...
Immobilizer Amplifier Replacement
Remove the upper fairing assembly (see Upper Fairing
Assembly Removal in the Frame chapter).
Disconnect the connector [A].
Pull out the immobilizer amplifier [B] together with the rubber
protector [C] from the air intake duct [D].
ECU Replacement
Refer to the ECU Removal/Instal ...