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 DiscESD (Electronic Steering Damper) ECU Communication Error (Service Code 3C,
ZX1000JD/KD)
ESD ECU Communication Line Inspection
When the data (for status of ESD system) is not sent from
the ESD ECU to the meter unit and ECU, the service code
3C is displayed.
The data is sent through the CAN communication line.
The service code 3C is detected with the meter unit.
The FI symbol does ...
Nozzle Assy Installation
Replace the dust seals [A] with new ones.
Apply engine oil to the new dust seals, and install them.
Install the nozzle assy securely.
Push the four mounting positions of the injectors.
Set the joint pipe parallel to the air cleaner housing [B].
NOTICE
When installing the nozzle assy, ap ...
Oxygen Sensor Heater Power Source Voltage Inspection
NOTE
Be sure the battery is fully charged.
Turn the ignition switch to OFF.
Remove the fuel tank (see Fuel Tank Removal in the Fuel
System (DFI) chapter).
Disconnect the oxygen sensor lead connector and connect
the measuring adapter [A] between these connectors
as shown in the fig ...