This type of engine has only one cylinder and will work best on little cc bikes. It's cheap to keep up and correct if anything goes wrong. In addition it generates high torque at reduced revs, that makes it appropriate for off-road and commuter bikes. Illustration: Splendor, Platina and perhaps https://bike-engine-number27134.blog-a-story.com/16013595/chair-lift-stairs-near-me-can-be-fun-for-anyone