Such a engine has only one cylinder and works best on smaller cc bikes. It really is cheap to take care of and correct if anything goes Mistaken. In addition, it creates high torque at low revs, that makes it well suited for off-road and commuter bikes. Case in point: https://bike-engine-2-stroke92570.digiblogbox.com/59639992/how-fast-does-a-212cc-predator-mini-bike-go-no-further-a-mystery