I lightened up a 750 Honda 4 cylinder years ago. had a 900cc bore kit, alloy rods, lightened alternator. running high compression, stiff valve springs. For it's time it was pretty fast. But, the engine did not want to keep spinning at low rpms. several drops in parking lots putting around as the engine would just not have enough weight to keep spinning and lock up tighter than a bulls ass in fly season. Lots of revs and slipping the stiff Barnet clutch, was the answer. On a small single cylinder engine like this I wonder with no flywheel if it would be rideable? Would need stiff springs in the clutch or TC to engage at high RPMS or a manual clutch. Might have to make a light weight alloy flywheel, play with weight until you got a balance between performance and rideability.