Replace the wheel rotation sensor if it is cracked, bent, or otherwise damaged.

Rear Wheel Rotation Sensor Installation
Wheel Rotation Sensor Air Gap InspectionCrankcase Halves Assembly
Install:
Crankshaft (see Crankshaft Installation)
Connecting Rods (see Connecting Rod Installation)
Using a cleaning fluid, clean off any oil or dirt on the mating
surface of the crankcase halves.
Apply liquid gasket to the mating surface of the lower
crankcase half as shown in the fi ...
Transmission Shaft Disassembly
Remove the transmission shafts (see Transmission Shaft
Removal).
Remove the circlips, and then disassemble the transmission
shafts.
Special Tool - Outside Circlip Pliers: 57001-144
The 5th gear [A] on the output shaft has three steel balls
assembled into it for the positive neutral fin ...
Check 2-1: Speedometer Inspection
Using the suitable stand, raise the rear wheel off the
ground.
Rotate the rear wheel by hand or start the engine.
Check that the display changes speedometer.
If the display function does not work, check the following
parts.
Rear Wheel Rotation Sensor (see Wheel Rotation Sensor
Inspe ...