Gearbox Age 16 upwards (Junior 13 – 16)

Other than the Junior 85cc category for 13-16 year olds which is only raced at one or two clubs, gearbox karts offer the highest powers and speeds. They can have either 2 pedals – brake and accelerator – like the direct drive classes, or 3 pedals, one of which is a foot clutch, like a car. Most 125’s use karts very similar to the direct drive karts except for the four wheel brakes. They have a hand clutch mounted next to the steering wheel, which is only used to move off from a standstill. At most circuits a standing start is used, as opposed to the rolling formation start that direct drive karts have.

Gearbox karts can also be used on the long motor racing circuits, although everyone should preferably start on the short circuits which are typically 900 to 1400 metres in length.


KZ UK is the most popular gearbox class. Although a little more expensive than a direct drive class, they can be surprisingly economical to run. The 125cc water cooled engines have six gears, sequentially operated like motorcycle using a gear-lever mounted next to the steering wheel. 0-60mph times are less than 3 seconds, top speed is 90mph on short circuit, 110 – 120mph on long circuit. The ABkC championship is promoted by the NKF. KZ2 is virtually the same but with more rigid regulations to CIK standard, and is the MSA British Kart Championship class but may not be run.

Junior Gearbox

This class uses an 85cc Honda or TM engine with 6 gears and is for 13-16 yrs.
With its four wheel braking it offers the youngsters an experience close to a single seater race-car. It’s not raced much at all now though. Currently only run in the Channel Islands.

250 National

This is the most powerful short-circuit class using 250cc single cylinder motocross 5- speed engines. The karts are often equipped with large full width nose cones and wings, especially when used on the long circuits. Top speeds are 100mph on short circuit, 140mph on long circuit. Twin cylinder Superkarts can reach 170mph though. The NKF holds the ABkC national championship. Some clubs offer the 450cc 4-stroke engine class which may be raced in parallel with 250 National but for separate prizes.

210 National

A classic class using the Villiers 197cc engine or derivatives. Administered by the drivers themselves through the 210 Challenge group, contact is Sian Masson email  .

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