I have the RCS 1.40 in A 13 pound 73 inch Extra and it has more then enough beans to fly this plane. Only problem is the carb is in the rear and may cause you to use that old thinking machine when you are setting up. Other then that it is just gas and go. No engine snot to clean up either. The price of A gallon of gas and A couple of ounces of oil is all it takes.