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 DiscOutline
When a problem occurs with DFI system, the warning indicator
light (LED) [A] and FI warning symbol [B] goes on
to alert the rider. In addition, the condition of the problem is
stored in the memory of the ECU. For models equipped with
an immobilizer system, the warning indicator light (LED)
and ...
Vehicle-down Sensor Installation
Be sure to install the rubber dampers [A] and collars [B]
on the bracket.
The UP mark [A] of the sensor should face upward.
WARNINGIncorrect installation of the vehicle-down
sensor
could cause sudden loss of engine power. The
rider could lose balance during certain ...
Engine Vacuum Synchronization Inspection
NOTE
These procedures are explained on the assumption that
the intake and exhaust systems of the engine are in
good condition.
Situate the motorcycle so that it is vertical.
Remove:
Fuel Tank (see Fuel Tank Removal in the Fuel System
(DFI) chapter)
Air Cleaner Housing (see Air Cleaner ...