I'm not master at centrifugal clutches, but I would assume that if it;s too tight, the engine will die when you stop the bike.
a centrifugal clutch should slip on take off, and then lock up once you get to a certain rpm or speed.
you shoudl be able to stop the bike and the clutch should slip enough to where the engine will still idle, and the bike doesn't move until you give it throttle again.
I'm not sure abou how the centrifugal clutches for these engines are, but I know that snowmobiles, mopeds, mini bikes and go karts all work this way.