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 InspectionSteering Damper Installation
Install the following parts as shown in the figure.
Collar [A]
Washer (t = 3.5 mm, 0.14 in.) [B]
Steering Damper [C] (
ZX1000JC/KC)
Electronic Steering Damper [D] (ZX1000JD/KD)
Washer (t = 1.2 mm, 0.05 in.) [E]
Apply a non-permanent locking agent to the threads of
the steering ...
Bolts, Nuts and Fasteners Tightness Inspection
Check the tightness of the bolts and nuts listed here. Also,
check to see that each cotter pin is in place and in good
condition.
NOTE
For the engine fasteners, check the tightness of them
when the engine is cold (at room temperature).
If there are loose fasteners, retighten them to ...
Piston Ring Thickness Inspection
Measure the piston ring thickness.
Use the micrometer to measure at several points around
the ring.
Piston Ring Thickness
Standard:
Top [A] 0.77 0.79 mm (0.0303
0.0311 in.)
Second [B] 0.78 0.79 mm
(0.0307 0.0311 in.)
Service Limit:
Top 0.70 mm (0.0276 in.)
Second 0.71 mm (0.0280 ...