Re: 90cc 2 strke cyclinder and piston kit?
You can do whatever you want, its a hobby, not a regulated industry. This is just a forum for discussing motorized bicycles. I'm not sure what you are trying to do.
Generally speaking, a motorized bicycle needs to be capable of moving when powered by a human only (think motor-assisted).
If I recall correctly the "death race" (a big motorized bicycle race in Tuscon, AZ which occurs yearly) is limited to 66cc engines.