Hi, new to the site. Got a schwinn chopper that I want to put a little engine it for my son. If everything goes OK, I'd like to do more bikes. Located in WA state, outside of Seattle. See a lot of engines, options, parts, etc. so before i start I'd love some advice from the community. I'd like to go with a 49cc four stroke but haven't really began my research as to what engine and by whom? Open to ideas. Anyone built this bike or have suggestions for me? How difficult is the build, good engine? disc brakes?, etc. etc.