KZ karts use what type of gearbox?

KZ karts use a six-speed sequential gearbox.

KZ is the primary gearbox class in CIK-FIA international karting. Its 125cc water-cooled two-stroke engine drives through a manually operated six-speed sequential transmission, allowing the driver to select gears in order rather than using an H-pattern car-style shift layout.

The gearbox is what separates KZ from direct-drive categories such as OK. KZ drivers can keep the engine in a stronger part of its power band through corners and straights, but the added mechanism also brings a clutch, shift linkage, and greater driving complexity. KZ regulations specify a manual clutch as well as the sequential gearbox.

The class evolved from Formula C, introduced internationally in 1974. Super-ICC replaced Formula C in 2002, KZ1 replaced it in 2007, and the category took the KZ name in 2013. KZ2 is a related secondary gearbox class with broadly similar engine and transmission concepts, though its chassis and equipment rules differ.