Four strokes can be a handful vibration wise. Your particular engine might just be one of the "shakers". I would check the specs. DP recommends no larger than a 63 4 stroke and has said that the YS 63 is too much for the plane. Your 72 is significantly larger. A recent review of this model used a Saito 72, and the magazine included a DP comment at the bottom stating that the engine was larger than he recommended. DP tends to design on the light side and when he recommends an engine size range I would seriously consider it unless I was prepared to beef up the model significantly. The plane's a good one, you might want to try a 56.