I looked at all your pictures, that is some pretty good messing around. I like the gas tanks you made, they look very good.
Wish I had your skill, I have never risen above the tinker level but I enjoy the hobby and started tinkering with these motorized bicycles in 1978. My first one was called a Bumble Bee. A real pain to start and keep running and it seemed just about everything broke at one time or another. But when I pulled it out of the back of my airplane ane it kept running I had a great time. Made it into an on and off hobby over the years.
You said you have sold several, are you still messing with motorized bicycles or have you stopped.