Replace it if necessary.

Inner Tube Inspection
Spring Tension InspectionMaster Cylinder Rubber Parts Replacement
Front Master Cylinder Disassembly
Remove the front master cylinder (see Front Master Cylinder
Removal in the Brakes chapter).
Remove the seal cover [A], circlip [B], connector [C] and
O-ring [D].
Special Tool - Inside Circlip Pliers: 57001-143
Unscrew the locknut [E] and pivot bolt ...
Upper Fairing Assembly Disassembly
Remove:
Upper Fairing Assembly (see Upper Fairing Assembly
Removal)
Headlight (see Headlight Removal/Installation in the
Electrical System chapter)
City Light (LED) (see City Light (LED) Removal/Installation
in the Electrical System chapter)
Remove the screws [A], and separate each ...
Front Master Cylinder Installation
Apply silicone grease to the sliding surface of the brake
lever pivot bolt.
Tighten:
Torque - Brake Lever Pivot Bolt: 1.2 N·m (0.12 kgf·m, 11
in·lb)
Brake Lever Pivot Bolt Nut: 5.9 N·m (0.60 kgf·m,
52 in·lb)
Assemble the reservoir [A] and the bracket [B] as shown
in the figu ...