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 DiscGear Position Switch Inspection
NOTE
Be sure the transmission and external shift mechanism
are good condition.
Remove the fuel tank (see Fuel Tank Removal in the Fuel
System (DFI) chapter).
Disconnect the connector [A].
Set the hand tester [A] to the × 1 kΩ or × 100 Ω range
and connect i ...
Meter Unit Circuit (ZX1000J Model)
1. Ignition Switch
2. Joint Connector F
3. Stop Watch Button
4. Oil Pressure Switch
5. Crankshaft Sensor
6. Water Temperature Sensor
7. Gear Position Switch
8. Intake Air Temperature Sensor
9. ESD ECU (ZX1000JD/KD)
10. ECU
11. Rear Wheel Rotation Sensor
12. Engine Ground
13. Battery ...
Brake Pedal Installation
Apply grease to the brake pedal pivot shaft [A].
Install:
Washers [B]
Brake Pedal [C]
Apply a non-permanent locking agent to the threads of
the brake pedal mounting bolt [D], and tighten it.
Torque - Brake Pedal Mounting Bolt: 8.8 N·m (0.90 kgf·m,
78 in·lb)
Install the re ...