I have an OS 52 4 stroke in my 4*40 ARF and it is great. This was my 2nd airplane and my first taildragger and I didn't feel the need to overpower it. I still have plenty of power to get myself in trouble. My landings are sometimes less than perfect and I do lots of to & landings practicing and finally the tail wheel wire failed from constant straightening. I would start out with a Sullivan tailwheel assembly from the start. My .02cents.