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 finder mechanism.
Remove the 5th gear as follows.

Set the output shaft in a vertical position holding the 3rd gear [B].
Spin the 5th gear quickly [C] and pull it off upward.
Transmission Assy Installation
Transmission Shaft AssemblyThrottle Body Assy Installation
Apply a thin coat of grease to the throttle cable lower ends.
Fit the accelerator cable end [A] and the decelerator cable
end [B] into the throttle pulley.
Install the clamp [C] securely.
Install the throttle body assy holder clamp bolt heads [A]
outside as shown in the figure.
...
Periodic Maintenance Chart
The scheduled maintenance must be done in accordance with this chart to keep
the motorcycle in
good running condition. The initial maintenance is vitally important and must
not be neglected.
Periodic Inspection
#: Service more frequently when operating in severe conditions; dusty, ...
Intake Air Temperature Sensor Resistance Inspection
Remove the intake air temperature sensor (see Intake Air
Temperature Sensor Removal).
Suspend the sensor [A] in a container of machine oil so
that the heat-sensitive portion is submerged.
Suspend a thermometer [B] with the heat-sensitive portion
[C] located in almost the same depth with ...