Well mine would have balanced perfectly if this fat bear wouldn't have crawled in the cockpit. I have an O.S 91 4 stroke in the teal/white Hog Bipe I just recently built. I also used a Saito 100, and a Magnum 91 4 stroke in my earlier Light Blue/White Hog Bipe I built. I have found that all 3 engines provide ample power for the Plane, and they balance well with any of those three engines. As I said, I do have some lead in the nose of my new Hog Bipe, but only because I have a fat pilot sitting behind the cg.