ORIGINAL: optech
I've not been following .21 size engine development but aren't they all ABC style construction nowadays? If so, they wont last long on Gasoline fuel. The ABC construction is pretty temperature specific when running. Gas burns hotter so I wouldn't expect the engine to last long. Look for a ringed type engine if you really want to do this.
Mike
Hmm, the engine I have is of ABC construction, like you mentioned. I guess this could cause some problems [:@]. Do you think I could avoid this by keeping it as cool as possible (using a cooling fan and avoiding full throttle), and use a higher oil content? If the engine does end up dieing, I will definately upgrade to a bigger, ringed engine.