If a master cylinder or piston shows any damage, replace them.

If a cup is worn, damaged softened (rotted), or swollen, the piston assembly should be replaced to renew the cups.
If fluid leakage is noted at the brake lever, the piston assembly should be replaced to renew the cups.
If they are damaged, replace them.
If the springs are damaged, replace them.
If the relief port becomes plugged, the brake pads will drag on the disc. Blow the ports clean with compressed air.
Front Master Cylinder [I] Rear Master Cylinder [J]

Rear Master Cylinder Installation
Brake DiscBrake Fluid Level Inspection
Check that the brake fluid level in the front brake reservoir
[A] is above the lower level line [B].
NOTE
Hold the reservoir horizontal by turning the handlebar
when checking brake fluid level.
If the fluid level is lower than the lower level line, fill the
reservoir to the upper lev ...
Compression Damping Force Adjuster and Rebound
Damping Force Adjuster Adjustment
The compression damping force adjuster
and the rebound damping force
adjuster are located on top of each front
fork leg.
Turn the adjuster clockwise with a
screwdriver to increase damping
force.
Turn the adjuster counterclockwise
to decrease damping force.
NOTICE
Do not force to t ...
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 ...