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 DiscAlternator Rotor Installation
Using a cleaning fluid, clean off any oil or dirt on the following
portions and dry them with a clean cloth.
Crankshaft Tapered Portion [A]
Alternator Rotor Tapered Portion [B]
Install the alternator rotor.
Using a cleaning fluid, clean off any oil or dirt on the
washer [A] ...
Stem, Stem Bearing Removal
Remove:
Upper Fairing Assembly (see Upper Fairing Assembly
Removal in the Frame chapter)
Front Fender (see Front Fender Removal in the Frame
chapter)
Front Wheel (see Front Wheel Removal in the
Wheels/Tires chapter)
Steering Stem Head with Handlebars (see Handlebar
Removal)
Fron ...
Lower Fairing Installation
Installation is the reverse of removal. Note the following.
When installing the pad [A], align the edge of the pad and
the marking of the fairing [B].
When installing the pad [C], align the edge of the pad and
the fairing [D], and fit the edge of the pad to the boss [E].
Insert the hoo ...