Build a go-kart using readily available parts and a lawn mower engine. This is a very simple design built with junk yard scavenged parts mostly. Remember web uilt this as kids, the dimensions would alter somewhat for bigger riders.
How to Create a Go Kart with a Lawnmower Engine. Though go-karts traditionally use horizontal mount engines, with a little modification, you can install a vertical shaft lawnmower engine to be the driving force behind your homemade racing.