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 DiscOil Filter Replacement
Drain the engine oil (see Engine Oil Change).
Remove the left lower fairing (see Lower Fairing Removal
in the Frame chapter).
Remove the oil filter [A] with the oil filter wrench [B].
Special Tool - Oil Filter Wrench: 57001-1249
Replace the filter with a new one.
Apply grease t ...
Upper Crankcase Assembly
When installing the breather plate, replace the gasket [A]
with a new one.
Apply a non-permanent locking agent to the threads of
the bolts [A] and tighten them.
Torque - Breather Plate Bolts: 9.8 N·m (1.0 kgf·m, 87 in·lb)
Install the fitting [A] until it is bottomed ...
KIBS Motor Relay Inspection (Service Code b 35)
Check the KIBS motor relay fuse (25 A) [A] (see Fuse
Inspection in the Electrical System chapter)
If the fuse is good, check the wiring continuity as follows.
Disconnect:
Battery Positive Cable (see Battery Removal in the Electrical
System chapter)
KIBS Hydraulic Unit Lead Connector (see ...