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 DiscRadiator and Radiator Fan Removal
Remove:
Upper Fairing Assembly (see Upper Fairing Assembly
Removal in the Frame chapter)
Coolant (Drain, see Coolant Change in the Periodic
Maintenance chapter)
Air Cleaner Housing (see Air Cleaner Housing Removal
in the Fuel System (DFI) chapter)
Coolant Reserve Tank (see Coolant R ...
Fuel Injector Fuel Line Inspection
Remove:
Fuel Tank (see Fuel Tank Removal)
Air Cleaner Housing (see Air Cleaner Housing Removal)
Disconnect:
Primary and Secondary Fuel Hoses (see Fuel Hose Replacement
in the Periodic Maintenance chapter)
Do not remove the nozzle assy from the air cleaner housing.
Be sure to pla ...
Chassis Parts Lubrication
Before lubricating each part, clean off any rusty spots with
rust remover and wipe off any grease, oil, dirt, or grime.
Lubricate the points listed below with indicated lubricant.
NOTE
Whenever the vehicle has been operated under
wet or rainy conditions, or especially after using a
high ...