I wouldn't go putting a much bigger engine than recommended in the UCD anyway. The airframe is built light enough that it can hover on the recommended engine. If you over power it, you will have structural failure. The UCD is not built for high speed flight, and it can't handle it, so be sure to stay on the throttle and don't let the airspeed build up. Beyond that, you should be fine flying it. Check the instructions about prop selection as well. A 6" pitch prop is more than you need, you're better off with a larger diameter, smaller pitch prop.