The Mach I was a direct result of the widespread success of the Kawasaki H1 Mach III 500 cc introduced in 1969.

The Mach I's engine was a three-cylinder two-stroke with an engine displacement of 249 cc (15.1 cubic inches) which produced 32 bhp at 8,000 rpm, a power-to-weight ratio of 1 hp (0.75 kW) to every 11.8 pounds.

[citation needed] The S1 Mach I replaced the twin Kawasaki A1 Samurai 250 with its twin-cylinder, Kawasaki rotary disc valve engine which produced 31 hp (23 kW) at 8,000 rpm.

It was essentially the same motorcycle as its larger brother with less displacement.

It had a separate handlebar holder and steering friction damper.