I remove the bolts securing the bearing plate behind the flywheel. Flywheel, Bellhousing, Governor weight mechanism, Piston, rod and cylinder removed of course.
Set the crankcase with crankshaft up in the press, supported outside the OD of the bearing plate. The crankcase will need to be elevated approximately 3" to allow the crankshaft and bearing plate to move downward.
Press the end of the Crankshaft only... Not the gear. I use a socket that is a bit smaller than the end of the crankshaft inside the gear, to press against.
The Crankshaft and bearing plate will come out the back of the crankcase, leaving the gear behind.
I use a 12 ton press for removal and installation of the gear.