If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterAir Switching Valve Removal
NOTICE
Never drop the air switching valve especially on a
hard surface. Such a shock to the air switching
valve can damaged it.
Remove the air cleaner housing (see Air Cleaner Housing
Removal in the Fuel System (DFI) chapter).
Disconnect the connector [A].
Disconnect the hoses [B] from ...
Wiring Diagram (Other than US, CA and CAL without KIBS Models)
ZX1000JC
ZX1000JD
...
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 ...