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 DiscMoving Off
Check that the side stand is up.
Pull in the clutch lever.
Shift into 1st gear.
Open the throttle a little, and start to
let out the clutch lever very slowly.
As the clutch starts to engage, open
the throttle a littlemore, giving the engine
just enough fuel to keep it from
stallin ...
Clutch Removal
Remove:
Clutch Cover (see Clutch Cover Removal)
Clutch Spring Bolts [A]
Clutch Springs (with Clutch Spring Holders)
Clutch Spring Plate [B]
Pusher [C]
Remove:
Friction Plates (10) [A]
Steel Plates (9) [B]
Spring [C]
Spring Seat [D]
Hold the sub clutch hub [A] ...
ABS Indicator Light (For models equipped with KIBS)
: Normally
the ABS indicator light goes on when the ignition switch is turned
“ON” and goes off shortly after the motorcycle starts moving. If the ABS is
normal,
it stays off. If the ABS indicator light shows any of the following, a fault or
faults may
have taken place in the ABS. You ...