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 InspectionCylinder Head Warp Inspection
Clean the cylinder head.
Lay a straightedge across the lower surface of the cylinder
head at several positions.
Use a thickness gauge [A] to measure the space between
the straightedge [B] and the head.
Cylinder Head Warp
Standard: – – –
Service Limit: 0.05 mm (0.0020 in.)
...
Charging Voltage Inspection
Check the battery condition (see Charging Condition Inspection).
Warm up the engine to obtain actual alternator operating
conditions.
Remove the front seat (see Front Seat Removal in the
Frame chapter).
Check that the ignition switch is turned off, and connect
the hand tester [A] to t ...
Brake Disc Warp Inspection
Raise the wheel off the ground with the jack.
Special Tools - Jack: 57001-1238
Jack Attachment: 57001-1608
For front disc inspection, turn the handlebar fully to one
side.
Set up a dial gauge against the disc [A] as shown in
the figure and measure disc runout, while turning [B] the
...