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 DiscCheck 3-4: Turn Signal Indicator Light (LED) Inspection
Connect the leads in the same circuit as Check 3-2.
Connect the terminal [5] to the battery (+) terminal.
Connect the terminal [6] to the battery (+) terminal.
Check that the turn signal indicator light (LED) [A] goes
on.
If the indicator light does not go on, replace the meter ...
Self-Diagnosis Outline
The self-diagnosis system is monitoring the following
mechanisms.
DFI System and Ignition System
S-KTRC System
Immobilizer System (Equipped Models)
KIBS and ABS (Equipped Models)
ESD (Electronic Steering Damper) System
(ZX1000JD/KD)
The following warning indicator lights (LED) are used for ...
Oil Cooler Installation
Replace the O-ring [A] with a new one.
Apply grease to the new O-ring.
Install the water hoses and hose clamps [A] as shown in
the figure.
Water Hose (About 300 mm, 11.8 in.) [B]
Water Hose (About 130 mm, 5.1 in.) [C]
Yellow Paint [D]
Tighten:
Torque - Water Hose Clamp S ...