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 Inspection
Remove the radiator (see Radiator and Radiator Fan Removal).
Check the radiator core.
If there are obstructions to air flow, remove them.
If the corrugated fins [A] are deformed, carefully
straighten them.
If the air passages of the radiator core are blocked more
than 20% by unremovable ...
Pressure Testing
Remove:
Upper Fairing Assembly (see Upper Fairing Assembly
Removal in the Frame chapter)
Radiator Cap [A]
Remove the radiator cap in two steps. First turn the cap
counterclockwise to the first stop. Then push and turn it
further in the same direction and remove the cap.
Install the ...
Valve Clearance Inspection
NOTE
Valve clearance must be checked and adjusted when
the engine is cold (at room temperature).
Remove:
Crankshaft Sensor Cover (see Crankshaft Sensor Removal
in the Electrical System chapter)
Cylinder Head Cover (see Cylinder Head Cover Removal
in the Engine Top End chapter)
Turn t ...