The oil pump drive gear bolt is left-hand threads.

Oil Pump Installation
Oil Pump Drive Gear InstallationClutch Installation
Apply engine oil to the needle bearing [A] and the sleeve
[B].
Install:
Needle Bearing
Sleeve
Install the clutch housing [A].
Fit the holes [B] and projections [C].
Engage the clutch housing gear and the crankshaft primary
gear.
Install the spacer [A] and the clutch ...
For Primary Fuel Injectors
Remove the air cleaner housing (see Air Cleaner Housing
Removal).
Disconnect the injector connector and connect the harness
adapter [A] between these connectors as shown in
the figure.
Main Harness [B]
Primary Fuel Injector #1 [C]
Special Tool - Measuring Adapter: 57001-1700
...
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 ...