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 DiscTroubleshooting Guide
NOTE
Refer to the Fuel System chapter for most
of DFI trouble shooting guide.
This is not an exhaustive list, giving every
possible cause for each problem listed. It
is meant simply as a rough guide to assist
the troubleshooting for some of the more
common difficulties.
Engine Doe ...
Intake Air Pressure Sensor #1 Removal
NOTICE
Never drop the intake air pressure sensor #1 especially
on a hard surface. Such a shock to the sensor
can damage it.
Remove:
Air Cleaner Housing (see Air Cleaner Housing Removal
in the Fuel System (DFI) chapter)
Intake Air Pressure Sensor #1 Connector [A]
Remove the intake air ...
Battery Installation
Place the battery in the battery case.
Connect the (+) cable to the (+) terminal,
and then connect the (–) cable
to the (–) terminal.
NOTICE
Installing the (–) cable to the (+)
terminal of the battery or the (+)
cable to the (–) terminal of the
battery can seriously damaged
...