Karting??..

I did a lot of 5hp Briggs stuff in the 90's. All of the R&D I did went out the window when the Briggs Animal was adopted by the AKF. Those made a lot of torque. They sounded like Jr Harleys, in a since. LOUD !
There's a clay quarter mile (yes 1/4 mile!) super speedway close to where I grew up. One could get seriously hurt if you hooked a tire on that track.