The Kawasaki GPZ900R is a motorcycle that was manufactured by Kawasaki from 1984 to 2003. It is the earliest member of the Ninja family of sport bikes. The 1984 GPZ900R was a revolutionary design that became the immediate predecessor of the modern-day sport bike. Developed in secret over six years, it was Kawasaki's and the world's first 16-valve liquid-cooled inline four-cylinder motorcycle engine.

The Kawasaki Z1 is a four-cylinder, air-cooled, double-overhead camshaft, carbureted, chain-drive motorcycle introduced in 1972 by Kawasaki. Following the introduction of Honda's CB750 in 1968, the Z1 helped popularize the in-line, across-the-frame four-cylinder, a format that became known as the Universal Japanese Motorcycle or UJM.