[OLDKID]

A sprocket on a centrifugal clutch , and a sprocket on the axle works on a street kart where once you get rolling it's all about maintaining speed . But in a yard kart , buggy , etc. It has to be capable of providing the proper ratio of power versus resistance ... The Torque Converter ! Think of it as an automatic variable speed automatic transmission , or you / the motor ... Riding a 10 speed bike / the Kart .... And the torque converter shifts the gears seamlessly and automatically to keep engine from lugging ,or excessively over revving . A centrifugal clutch and sprocket would just fry the clutch if used in such an application. .