Reverse Gearbox Transmission for Go-Karts with TAV2 Series 30 Torque Converters. A reverse gearbox is commonly used on small and medium-size go-karts with 5.5 HP and 6.5 HP engines. Unlike 2-wheel powersports equipment using similar engine displacement, go-karts, dune buggies, and ATVs usually have need of a reverse gear.