I started out with an OS 70 4 stroke on mine. Everyone told me to "open it up". I told them it IS opened up!

I parked it until my new OS 91 surpass 4 stroke arrived and I have never looked back since. Use a 14-6 apc prop and the 91 pulls the Hog around with authority. No oily mess to clean up afterwards either with the 4 stroke.