I have a feeling the lack of responsiveness is the governor. I did try to adjust it a bit. Not much change. I didn’t want to play with it too much considering it was running. Just slow acceleration
Float adjustment is 11/64 drill bit. I always set for level on a stock engine, as you will never burn the fuel from the bowl like that, and it wont leak out of the top vent at level.
I adjust the high speed needle for acceleration against the clutch. In other words, I rev the throttle fast, holding the bike, against the centrifugal clutch. I turn it (lean usually} until I get a smooth acceleration. Once you do this, the high end will take care of itself. You will readily note it smoothing out under quick acceleration. No need to remove chain or elevate the bike. What happens when you do that, is you get an optimum WOT, but your acceleration is boggy, or stumbles. Moreover, you can't adjust WOT on anything without a load, because you are not working the engine. WOT with no load is too lean for WOT with a rider.
I never run these engines with no load against the governor.
To adjust the governor, you need to first ensure your spring is in good shape, and that no slop or friction exists in the throttle rod.
These are the steps I use to get Maximum governed RPM: Loosen up the 1/4" hex screw that holds the 2 pieces of the governor arm together.
Rotate the governor rod coming out of the block clockwise with some pliers or a small crescent wrench. DON'T force it.
Keeping the rod rotated, push the top of the governor arm to the right to cause the throttle to open to “wide open throttle. “
Holding all of that, re-tighten the ¼” hex screw.
Basically the governor rod coming out of the engine is all the way to the right when the throttle is all the way to the right.
Naturally this needs to be done with all links/springs in place and if you change anything you need to re-adjust as described.