Use a vernier caliper at several points around the piston.
Piston Ring Groove Width Standard:
Top [A] 0.82
0.84 mm (0.0323
0.0331 in.)
Second [B] 0.82
0.84 mm
(0.0323
0.0331 in.)
Service Limit:
0.92 mm (0.036 in.)
Second 0.92 mm (0.036 in.)

If the width of any of the two grooves is wider than the service limit at any point, replace the piston.
Piston Ring, Piston Ring Groove Wear Inspection
Piston Ring Thickness InspectionFront Wheel Rotation Sensor Signal (Service Code 27)
Front Wheel Rotation Sensor Signal Inspection
The front wheel rotation sensor sends the signal to the
ECU through the KIBS hydraulic unit (KIBS equipped
models). For other than KIBS equipped models, the
signal is sent directly to the ECU.
The ECU uses the wheel rotation sensor signal for KTRC
...
Spring Preload Adjustment
To adjust the spring preload, turn the spring preload adjuster
[A].
The standard adjuster setting is the 6 turns in from the
fully counterclockwise position.
WARNINGIf both adjusters are not adjusted
equally, handling
may be impaired and a hazardous condition may
result. B ...
Brake 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
...