My first build well at least for motorized bicycles since I was a teenager was a Huffy Cranbrook with a china Girl 66cc engine last November
I have build cars and motorcycles but since being semi retired I needed something to occupy my time.
I got my first engine from a friend that had it and no desirte to put it on a bike so I jumped up and built the Crannie.
Since then I have put several together for friends and have to keep them running for them.
I think the thing I would have done differently would have been to make a 4 stroke with a centrifugal clutch as my first build simply for the reliability factor and I probably would not be having to work on OPBs all of the time cutting into my riding...
Not to say I wouldn't have built a China Girl. I do love them but my friends would have seen the 4 smokers first and been hooked on them instead and I would be riding more instead of wrenching.