I completed my first build a couple of months ago (49cc on a Kulana Hiku cruiser). This also is a heavy bike. I can now take off without pedaling, just by grabbing a handful of throttle and dumping the clutch. I made this possible by adding an expansion chamber (huge difference in low end torque), boost bottle and leaned out my jetting. I have found the machine is running better the more I ride it, and running a 25 to 1 mix vs the 18 to 1 break in mix has also improved performance. I have about a 100 miles on the engine at this point.