The Kawasaki Z1 is a four-cylinder, air-cooled, carbureted, chain-drive, two passenger motorcycle introduced in 1972 by Kawasaki. Following Honda's 1969 CB750, the Z1 helped popularize the in-line, cross-frame four-cylinder a format that became well known as the Universal Japanese Motorcycle or UJM.
The Z1 was noted for combining elements available previously on numerous motorcycles, into a single motorcycle.
Marketed variously as the Z900, 900 Z1 or 900 S4 ("Super Four"). the Z1 was the first Kawasaki's Z models.
The Kawasaki Z1 was developed under the project name "New York Steak". In the late 1960s Kawasaki, already an established manufacturer of two-stroke motorcycles, had begun prototyping a 750 cc four-cylinder four-stroke sports motorcycle working with McFarlane Design in 1969 to develop the bikes overall appearance. When Honda introduced the CB750 to the market first, Kawasaki postponed the Z1's release until its displacement could be increased to 903 cc and the motorcycle could be marketed in the 1000cc-class.