Hey guys. I have this enya 15-IV engine that i got from a garage sail and know nothing about. My main question is whether its an ABC or ringed engine. Also, How would I tell the difference between a ringed or ABC engine visually?
If you remove the muffler and look into the exhaust port you can see the side of the piston. Rotate the engine slowly until you see the top edge. A ringed engine will have the ring visible at this point. An ABC will have a solid piston. However, I believe that the engine you have is a "lapped" type. It's similar to ABC but has a lapped piston, usually aluminum in an iron sleeve. In any event, keep your nitro low at first 10 - 15% and it should be a good runner.
Here's a link to some good info regarding your Enya: