NOTE
Be sure the transmission and external shift mechanism are good condition.

When changing the gear position from lower gear to higher gear, raise the rear wheel off the ground with the stand and rotate the rear wheel by hand.
Internal Circuit [C]
[1] LG Lead [2] G/R Lead [3] BK Lead
Special Tool - Hand Tester: 57001-1394

Gear Position Switch Resistance

If the tester reading is not as specified, replace the gear position switch with a new one.
Gear Position Switch Installation
Relay BoxCharging Voltage Inspection
Check the battery condition (see Charging Condition Inspection).
Warm up the engine to obtain actual alternator operating
conditions.
Remove the front seat (see Front Seat Removal in the
Frame chapter).
Check that the ignition switch is turned off, and connect
the hand tester [A] to t ...
Tachometer
The tachometer shows the engine
speed in revolutions per minute (r/min,
rpm).
On the right side of the tachometer
face is a portion called the “red zone”.
Engine r/min (rpm) in the red zone is
above maximum recommended engine
speed and is also above the range for
good performance.
...
Shift Fork Guide Pin/Drum Groove Wear Inspection
Measure the diameter of each shift fork guide pin [A], and
measure the width [B] of each shift drum groove.
If the guide pin on any shift fork is less than the service
limit, the fork must be replaced.
Shift Fork Guide Pin Diameter
Standard: 6.9 7.0 mm (0.272
0.276 in.)
Service Limit: ...