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 DiscSubthrottle Valve Actuator Inspection
NOTE
Be sure the battery is fully charged.
Remove the air cleaner housing (see Air Cleaner Housing
Removal in the Fuel System (DFI) chapter).
Turn the ignition switch to ON.
Check to see that all the subthrottle valves [A] open and
close smoothly.
Turn the ignition switch to OFF.
I ...
Electronic Steering Damper Warning Indicator Light
The yellow light functions as the
electronic steering damper warning indicator.
The light and warning symbol
"ESD" go on if there is a malfunction in
the electronic steering damper system.
However, this could also be caused by
trouble with the charging system (e.g.
battery). I ...
Check 2-2: Fuel Level Warning Inspection
Remove:
Fuel Tank (see Fuel Tank Removal in the Fuel System
(DFI) chapter)
Connect the resistor(s) [A] (about 50 to 100 Ω) between
the fuel pump connector terminal [B] of the main harness
side and the battery negative (–) terminal [C] as shown.
Turn the ignition switch ...