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

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblyAir Switching Valve
Air Switching Valve Operation Test
Refer to the Air Suction System Damage Inspection in the
Periodic Maintenance chapter.
Air Switching Valve Unit Test
Remove the air switching valve (see Air Switching Valve
Removal in the Engine Top End chapter).
Set the hand tester [A] to the × 1 ...
Switch Inspection
Using a hand tester, check to see that only the connections
shown in the table have continuity.
Special Tool - Hand Tester: 57001-1394
For the switch housings and the ignition switch, refer to
the tables in the Wiring Diagram.
If the switch has an open or short, repair it or replace it
w ...
Balancer Installation
Position the crankshaft at #2, 3 positions TDC or at #1, 4
positions TDC.
Install the balancer assembly as follows.
Align the punch mark [A] on the weight and the projection
[B] on the crankcase.
Engage the balancer gear and the crankshaft gear.
Insert the balancer shaft until it is bot ...