I have the 30 cc Valiant with the Evolution 33gx gas motor and love it. I followed the instruction manual on setting up the 33gx motor and used regular gasoline and redline racing oil at 32:1 mix for break-in. It took almost two gallons of gas before breaking was starting to happen. I flew this model all last summer with this setting and gas/oil mixture and now am able to hand start this engine quit easily. I think it took longer to break in than a dle 30cc engine. This engine has plenty of power for the 30cc Valiant and will probably have plenty of power for the Hanger 9 1/4 scale super cub. By the way, I have the super cub bungee landing gear with 6" balloon wheels on my Valiant. Love this airplane.