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 DiscImmobilizer System (Equipped Models)
This motorcycle is equipped with an immobilizer system to protect the
motorcycle from theft. This
system provides a theft proof device by means of matching a code between the
inbuilt key transponder
and ECU. If the code does notmatch, ignition system, injectors, subthrottle
valve actuator an ...
Master Cylinder Rubber Parts Replacement
Front Master Cylinder Disassembly
Remove the front master cylinder (see Front Master Cylinder
Removal in the Brakes chapter).
Remove the seal cover [A], circlip [B], connector [C] and
O-ring [D].
Special Tool - Inside Circlip Pliers: 57001-143
Unscrew the locknut [E] and pivot bolt ...
Shift Pedal Removal
Remove:
Shift Lever Bolt [A]
Front Footpeg Bracket Bolts [B]
If the tie-rod [C] is to be removed from the shift pedal and
the shift lever, loosen the tie-rod locknuts [D].
The front tie-rod locknut is left-hand thread.
Remove:
Shift Pedal Mounting Bolt [A]
...