Pull start engine
In regard to the jack shift setups and difficulties in bump starting the engines...
It would seem to me that it might simplify starting if you had a pull start option on the motor. I don't have the jack shaft setup, but did recently buy an 80cc dual start motor for an additional bike. My other one is just the bump start. I find that I really like the pull start... I start it up and shut off the choke, let it run a bit to warm up and pedal away, letting out the clutch as I give it gas. None of this fumbling around as I go, trying to shut off the choke as I ride or on a cold morning leaving it open part way for a bit. The temptation is to look away from the road at the engine while fiddling, so for me at least it is a safer setup. It is also nice when you find yourself at the dip in a hill and have to pedal or walk the bike uphill to bump start it. So I like it. I did not like the hassles involved due to the wider engine and conflicts with the pedal crank. I had to raise my engine up above the arc of the pedal to get it installed on a 63 Schwinn American. But now that it is installed it is a sweet, hassle free ride.