I've been motorizing bikes and other contraptions all my life but have only begun using bike engine kits about 3 months ago. It's a different ballgame. I purchased a 4 stroke kit and half of the parts were missing or the wrong parts, so it has taken me this long to round up all the correct parts and install the kit on my Schwinn. I finished today and took the bike for a test drive. I made it around the block once and was doing ok. On the second round, a pin or key sheared off on the small gear inside that turns the final drive sprocket. I was supposed to have gotten a different gear box on this Hua Sheng engine, but the seller sent me the much more inferior JL Hoot kit with a very bad gearbox. I'm now hoping to find out which gearbox out there is higher quality and how I can get one that will bolt on to this engine. Looking inside this JL Hoot's gearbox, it wreaks of poor quality. Hopefully I can find something better. My bike is a Schwinn Point Beach.