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

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblyIdle Speed Inspection
Start the engine and warm it up thoroughly.
With the engine idling, turn the handlebar to both sides
[A].
If handlebar movement changes the idle speed, the
throttle cables may be improperly adjusted or incorrectly
routed, or damaged. Be sure to correct any of these
conditions before rid ...
Mud Guard Installation
Installation is the reverse of removal. Note the following.
Run the hose and lead correctly (see Cable, Wire, and
Hose Routing section in the Appendix chapter).
Check the brake line.
Apply a non-permanent locking agent to the threads of
the mud guard mounting bolts [A, B], and tighten them ...
Drive Chain
The drive chain slack and lubrication
must be checked each day before riding
the motorcycle and must be maintained
in accordance with the Periodic
Maintenance Chart for safety and to
prevent excessive wear. If the chain
becomes badly worn or maladjusted -
either too loose or too tight - the c ...