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 DiscAir Switching Valve
Air Switching Valve Operation Test
Refer to the Air Suction System Damage Inspection in the
Periodic Maintenance chapter.
Air Switching Valve Unit Test
Remove the air switching valve (see Air Switching Valve
Removal in the Engine Top End chapter).
Set the hand tester [A] to the × 1 ...
Relay Box Removal
Remove the left fuel tank cover (see Fuel Tank Removal
in the Fuel System (DFI) chapter).
Disconnect the connectors [A].
Pull out the relay box [B] from the rubber protector [C].
NOTE
The relay box has relays and diodes. The relays and
diodes can not be removed.
Relay Box Installa ...
Electrical Wiring
Wiring Inspection
Visually inspect the wiring for signs of burning, fraying,
etc.
If any wiring is poor, replace the damaged wiring.
Pull each connector [A] apart and inspect it for corrosion,
dirt, and damage.
If the connector is corroded or dirty, clean it carefully. If it
is da ...