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 DiscBrake Line Bleeding
The brake fluid has a very low compression coefficient so
that almost all the movement of the brake lever or pedal
is transmitted directly to the caliper for braking action. Air,
however, is easily compressed. When air enters the brake
lines, brake lever or pedal movement will be partially used
...
Technical Information - Electronic Steering Damper (ESD/ZX1000JD/KD models)
1) Overview
This model has an Electronic Steering Damper (ESD)
[A]. Unlike conventional manual adjustment method of
Kawasaki, damping characteristics are adjusted by the
electronic control unit.
2) Purpose
Designed to offer increased stability at high speed without interfering with
light ...
CAL and SEA-B1 Models
1. Green Hose (Purge)
2. Clamp (hold the white hose.)
3. Canister
4. White Hose (Vacuum)
5. Blue Hose (Breather)
6. Red Hose (Return)
7. Separator
8. Quick Rivet
9. Face the hook portion of the bracket to inside of the vehicle.
10. Clamp (Bend down the clamp, and hold the blue hose, the ...