Until the early 1960s, karts had the engine mounted behind the seat and above the axle. Then, with the arrival of air cooling systems and to lower the position of the engine, it was decided to move it to the side. The right side is theoretically the most convenient position because most of the tracks are right-handed and therefore the weight of the engine, inside a bend, counteracts the transfer of load, improving road holding. So all the manufacturers put it on the right. Nowadays, in reality the weight of a kart is in any case quite balanced because the seat is slightly to the left with respect to the centreline of the kart. But if you wanted to mount the engine on the left you couldn’t do it anymore, for a purely practical matter. In fact, engines all have the sprocket exit to the right and in that case you would end up with the chain facing the inside of the kart, not the best way to do maintenance!
