Hello from Jackson Michigan
Hey, nice website it has been very helpful with my first build, a 55cc Happy Time on a $69.00 Wal-Wart mountain bike. I built it about 1 month ago, and probably have about 550 miles on it.
I can tell these little happy time kits are kinda delicate and seem to need frequent tweaks, then again I have had to mess with it less and less, as i've been getting to know the bike.
I put a piece of cardboard inside the clutch cover for niose reduction, and stuck inch-long, 1/4x1/4 inch peices of tire rubber I cut up in between some of the fins too. It helped alot with niose reduction and possibly some vibration.
Fitting it to the frame was quite an arduous task as it was to small and the bottom pipe to thick, I ended up using a hack saw on the bottom pipe to make room for the bottom mount, hack-sawed the top bar to feed the throttle cabe through (otherwise carb would have to be tilted). In the end I couldn't get the bottom to mount with the hardware supplied and the hacked up frame. So I ended up using a pipe clamp that's wrapped around the block, (the bottom fin) to the frame, it has held up and hasn't moved, even after riding it down traintracks.