The Kawasaki 900 Super Four, better known as the Z1, debuted in 1972. Its 903 cc inline-four engine used air cooling and twin overhead camshafts. That layout became one of the defining features of Kawasaki’s large motorcycles.
In March 1973, three Z1s took part in record attempts at Daytona. The leading 24-hour result was about 4,233 km at an average 176.4 km/h. The overall effort produced 46 AMA and FIM records. Those figures reflect prepared machinery, a working team and closed-circuit conditions.
Interest in keeping the Z1 running later prompted a practical response. In 2019, Kawasaki announced a cylinder-head reproduction project for the Z1 and its Japanese-market relative, the Z2. The plan combined original drawings and specifications with modern manufacturing methods.
The Z1 therefore offers two ways into motorcycle history: the speed ambitions of the 1970s, and the importance of keeping an old engine serviceable long after its original production run.