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 InspectionCrankshaft Sensor Removal
Remove:
Fuel Tank (see Fuel Tank Removal in the Fuel System
(DFI) chapter)
Crankshaft Sensor Lead Connector [A]
Remove:
Right Lower Fairing (see Lower Fairing Removal in the
Frame chapter)
Bolts [A]
Crankshaft Sensor Cover [B] and Gasket
Oil Pressure Switch Terminal [C]
...
Check 3-1: CAN Communication Line Resistance Inspection
Set the hand tester [A] to the ×1 Ω range and connect it
to the terminal [11] and [12] in the meter unit.
Special Tool - Hand Tester: 57001-1394
CAN Communication Line Resistance (at Meter Unit)
Standard: 122 126 Ω
If the tester reading is not specified, replace the meter ...
Fuel Tank Cleaning
WARNINGGasoline and low flash-point solvents can
be
flammable and/or explosive and cause severe
burns. Clean the tank in a well-ventilated area, and
take care that there are no sparks or flame anywhere
near the working area. Do not use gasoline
or low flash-point solvents t ...