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 DiscValve Guide Installation
Apply engine oil to the valve guide outer surface before
installation.
Heat the area around the valve guide hole to about 120
150°C (248 302°F).
NOTICE
Do not heat the cylinder head with a torch. This will
warp the cylinder head. Soak the cylinder head and
heat the oil.
Usin ...
Self-Diagnosis Procedures
NOTE
Use a fully charged battery when conducting
self-diagnosis. Otherwise, the light (LED) and symbol
do not light or blink.
Turn the ignition switch to ON.
When a problem occurs with DFI system and ignition system,
the warning indicator light (LED) [A] goes on and
FI warning symbol ...
Idle Speed Control Valve Actuator Input Voltage Inspection
NOTE
Be sure the battery is fully charged.
Turn the ignition switch to OFF.
Disconnect the idle speed control valve actuator connector
and connect a suitable measuring leads [A] between
these connectors as shown in the figure.
Main Harness [B]
Idle Speed Control Valve Actua ...