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

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblyOil Pressure Measurement
Remove:
Right Lower Fairing (see Lower Fairing Removal in the
Frame chapter)
Oil Passage Plug [A]
Attach the adapter [A] and gauge [B] to the plug hole.
Special Tools - Oil Pressure Gauge, 10 kgf/cm²: 57001-164
Oil Pressure Gauge Adapter, PT3/8: 57001
-1233
...
Special Tools
Inside Circlip Pliers:
57001-143
Oil Seal & Bearing Remover:
57001-1058
Bearing Driver Set:
57001-1129
Jack:
57001-1238
Bearing Remover Head, 15 ×
17:
57001-1267
Fork Oil Level Gauge:
57001-1290
Bearing Remover Shaft, 13:
57001-1377
Fork Oil Seal Driver, 43:
57001-15 ...
Oil Level Inspection
Check that the engine oil level is between the upper [A]
and lower [B] levels in the gauge.
NOTE
Situate the motorcycle so that it is perpendicular to the
ground.
If the motorcycle has just been used, wait several minutes
for all the oil to drain down.
If the oil has just been changed, ...