If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterWiring Diagram (US, CA and CAL with KIBS Models)
ZX1000KC
ZX1000KD
...
Spring Tension Inspection
Since a spring becomes shorter as it weakens, check its
free length [A] to determine its condition.
If the spring of either fork leg is shorter than the service
limit, it must be replaced. If the length of a replacement
spring and that of the remaining spring vary greatly, the
remaining s ...
Steering Play Inspection
Remove the lower fairings (see Lower Fairing Removal in
the Frame chapter).
Raise the front wheel off the ground with the jack.
Special Tools - Jack: 57001-1238
Jack Attachment: 57001-1608
With the front wheel pointing straight ahead, alternately
tap each end of the handlebar. The f ...