RE: Propane
you know that would be pretty cool but yea..you need oil and you cant get oil in a gas...lol
but yea i`m sure this would be doable, and thing of the + like indoor running and CHEAPER fuel...lol
only thing is, you have to have it pressurized and that can be a problem if you hit something, unless you had a CF tank made[X(]
and you would have to use a 4-stroke since it has valves you wont waste any of the Gas
cuz if it was a 2-stroke it would just get to BDC and let all the pressure out..lol