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 InspectionPeriodic Maintenance Chart
K : Should be serviced by an authorized Kawasaki dealer.
* : For higher odometer readings, repeat at the frequency interval established
here.
# : Service more frequently when operating in severe conditions: dusty, wet,
muddy,
high speed, or frequent starting/stopping.
(e): Emission Rel ...
Fuse Box Fuse Removal
Remove the left upper inner fairing (see Upper Inner Fairing
Removal in the Frame chapter).
Unlock the hook [A] to take off the fuse box 1 [B].
Unlock the hook [C] to lift up the lid.
Pull the fuses [A] straight out of the fuse box 1 with needle
nose pliers.
Fuse Box 2
...
Shift Fork/Gear Groove Wear Inspection
Measure the thickness of the shift fork ears [A], and measure
the width [B] of the gear grooves.
If the thickness of a shift fork ear is less than the service
limit, the shift fork must be replaced.
Shift Fork Ear Thickness
Standard: 5.7 6.0 mm (0.224
0.236 in.)
Service Limit: 5.6 mm ...