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 InspectionBalance Inspection
Remove the front and rear wheels (see Front/Rear Wheel
Removal).
Support the wheel so that it can be spun freely.
Spin the wheel lightly, and mark [A] the wheel at the top
when the wheel stops.
Repeat this procedure several times. If the wheel stops
of its own accord in various positi ...
System Components
1. KIBS ECU
With input from the front and rear wheel sensors and front
caliper hydraulic pressure, the KIBS ECU analyzes various
conditions on the motorcycle, and with additional information
from the FI ECU (engine speed, throttle position, gear
position, and clutch actuation) precisely control ...
Information for Coolant
To protect the cooling system (consisting
of the aluminum engine and
radiator) from rust and corrosion, the
use of corrosion and rust inhibitor
chemicals in the coolant is essential. If
coolant containing corrosion and rust
inhibitor chemicals are not used, over
a period of time, the cooling ...