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

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblyLower Crankcase Assembly
Install the ball bearing [A] and the oil level inspection window
[B] until they are bottomed
Apply soap and water solution to the oil level inspection
window before installation.
Install the new circlip [C].
Apply a non-permanent locking agent to the oil passage
plug [D].
Tighten: ...
Clutch Cover Removal
Remove:
Right Lower Fairing (see Lower Fairing Removal in the
Frame chapter)
Clutch Cable Lower End (see Cable Removal)
Clutch Cover Bolts [A]
Turn the release lever [A] counterclockwise as shown,
and remove the clutch cover.
About 90В° [B]
...
Refreshing Charge
Remove the battery (see Battery Removal).
Do refresh charge by following method according to the
battery terminal voltage.
WARNINGThis battery is sealed type. Charge with
current and
time as stated below.
Terminal Voltage: 12.0 12.7
V
Standard Charge (see following ...