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 AssemblyInquiries to Rider
Each rider reacts to problems in different ways, so it is important to
confirm what kind of condition
the rider is dissatisfied with.
Try to find out exactly what problem occurs under exactly what
conditions by asking the rider; knowing
this information may help you reproduce the prob ...
Drive Chain Wear Inspection
Remove the chain cover (see Drive Chain Removal/Installation
in the Final Drive chapter).
Rotate the rear wheel to inspect the drive chain for damaged
rollers, and loose pins and links
If there is any irregularity, replace the drive chain.
Lubricate the drive chain if it appears dry.
...
Oil Pump Installation
Install the outer rotor [A] into the crankcase.
Assemble:
Oil (Water) Pump Shaft [B]
Pin [C]
Inner Rotor [D]
To prevent dropping, apply grease to the pin.
Install the inner rotor assembly into the crankcase.
Fit the slot [E] onto the projection [F].
Replace the O-ring [A ...