When it was introduced in 1972, Kawasaki marketed the Z1 as the most powerful four-cylinder, four-stroke motorcycle in the world. The 900cc monster is widely regarded as the first genuine Japanese superbike. The Z1 was the fastest production motorcycle in the world in 1973.

Since Kawasaki is quite popular in the motorsports market, its spare parts and accessories are readily available at relatively lower costs.

Z1 & Z900 engines have engine numbers stamped on the top right side crankcases on a raised area over the clutch. The engine numbers follow the same general range as the frame numbers although Frame and engine numbers were not matched at the factory.