Honda CB750 CB750K0–K8 (SOHC)

The CB750 put a transverse air-cooled inline-four, electric start and a front disc brake into a bike an ordinary buyer could finance, and the rest of the industry spent the next decade copying the layout. It is the template for what became the Universal Japanese Motorcycle. The first 7,414 engines used sand-cast cases and those bikes are the ones collectors chase; the rest of the K-series is a staple donor for cafe racer and drag builds.