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 DiscWiring Diagram (US, CA and CAL with KIBS Models)
ZX1000KC
ZX1000KD
...
Overview
Kawasaki Intelligent anti-lock Brake System (KIBS) offers enhanced braking
stability (ABS performance
equivalent to the current model) to supersportmodels, which pitch more than most
motorcycles
and also offers high-precision front and rear brake pressure control
(high-precision ABS) for spo ...
Oil Pump Drive Gear Installation
Install is the reverse of removal. Note the following.
First, engage the oil pump chain [A] to the gears, and then
install the oil pump drive gear [B].
Turn the “OUT” mark [C] to outside.
Apply a non-permanent locking agent to the oil pump drive
chain guide bolt and the oil pump drive ...