Superkart manufacturers produce specific 125cc chassis designed to cope with the far higher speeds, greater weight and far more powerful engines than their sprintkart cousins!

Due to the much higher speeds and kart/driver weight than sprintkarts, 125cc Superkarts are often fitted with aerodynamic aids such as rear wings and full bodywork!

The 125cc class is almost free of any technical regulations other than minimum kart/driver weights and some dimensional requirements. 4 wheel disc brakes are a requirement in this class of kart. 

There are few karts around now powered by Moto-X bike engines and still competing. These engines are in a much lower state of tune and the gearbox ratios do no suit well the extreme state of tune that makes a competitive 125cc Gearbox kart.

Honda RS 125cc GP motorcycle engines seem to be the predominant engine in this class, however older Rotax 125cc and TZ Yamaha 125cc engines occasionally appear. These little purpose made racing engines sing away at around 13500rpm and produce around 45 bhp through a 6 speed gearbox! The engines are in an extreme state of tune and require careful tuning and preventative maintenance, however being designed for the rigours of motorcycle road racing, are surprisingly reliable when fitted to a superkart, and with common sense will run for many kilometers between major rebuilds!

All engine modifications are allowed and due to the widespread use of Grand Prix motorcycle type engines, this class of kart probably suits the more technically minded competitor.

125cc Superkarts are identified by white racing numbers on a red background.