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 DiscPiston Wear Inspection
Measure the outside diameter [A] of each piston 5 mm
(0.20 in.) [B] up from the bottom of the piston at a right
angle to the direction of the piston pin.
If the measurement is under service limit, replace the piston.
Piston Diameter
Standard: 75.959 75.974 mm
(2.9905 2.9911 in.)
...
Power mode
The Power mode determines the engine
power output characteristics and
has three settings.
The S-KTRC and the Power mode
can be set separately. By combining
each setting, the rider can get various
power feelings to suit riding conditions
or individual preference.
Mode F (Full Power):
The h ...
Drive Chain Slack Inspection
Refer to the Drive Chain Slack Inspection in the Periodic
Maintenance chapter.
Drive Chain Slack Adjustment
Refer to the Drive Chain Slack Adjustment in the Periodic
Maintenance chapter.
Wheel Alignment Inspection/Adjustment
Refer to the Wheel Alignment Inspection in the Periodic
Maintenance ...