If the surface is corroded or if the blades are damaged, replace the impeller

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblyStem, 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 ...
Handlebar Installation
Apply a non-permanent locking agent to the threads of
the handlebar positioning bolts and tighten them.
Torque - Handlebar Positioning Bolts: 9.8 N·m (1.0 kgf·m,
87 in·lb)
Install the steering stem head with handlebars.
Install the washer [A] and steering stem head nut [B].
Tighten:
...
Location of parts
Clutch Lever
Left Handlebar Switches
Rebound Damping Force Adjuster
(Front Fork)
Compression damping force adjuster
(Front Fork)
Meter Instruments
Brake Fluid Reservoir (Front)
Right Handlebar Switches
Front Brake Lever
Throttle Grip
Ignition Switch/Steering Lock
Elect ...