From what I've been looking up , I'm thinking your right on the quadra. Still haven't figured out what size but I 'm bettig it's a 35.I'll keep researching.I put a new carb kit in it and it started right up!I had never heard of quadra, so I would have never figured that one out. Thanks!!I,m just glad it runs ok , I give $100 for the plane ,motor, and radio so I think I got a pretty good deal on it.The plane is in great shape but it has an old futaba model fp-t6fg/k radio with a fm module in it. I'll probably have to upgrade that but thats another thread ,I guess. Thanks!!