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 ...
Check 3-5: Warning Indicator Light (Red LED) (Oil Pressure Warning)
Inspection
Connect the leads in the same circuit as Check 3-2.
Connect the terminal [10] to the battery (–) terminal.
Check that the oil pressure warning symbol [A] and the
warning indicator light (Red LED) [B] go on.
If the indicator light does not go on, replace the meter unit.
...
Radiator Inspection
Remove the radiator (see Radiator and Radiator Fan Removal).
Check the radiator core.
If there are obstructions to air flow, remove them.
If the corrugated fins [A] are deformed, carefully
straighten them.
If the air passages of the radiator core are blocked more
than 20% by unremovable ...