The Kawasaki 750 H2 Mach IV Triple – a Technical History

In the late 1960s, Kawasaki Heavy Industries sought to assert itself as a dominant force in the global motorcycle market. With Honda’s CB750 having redefined the superbike class in 1969 by offering four-stroke reliability and refinement, Kawasaki responded not with imitation but with audacity: the development of a two-stroke, three-cylinder motorcycle with uncompromising performance. The result was the Kawasaki H2 Mach IV, a 750cc triple-cylinder two-stroke that debuted in 1972. It was the culmination of Kawasaki’s relentless pursuit of acceleration supremacy and became an icon of raw power and minimal restraint.

Genesis and Context

The H2 was a direct descendant of the Kawasaki H1 Mach III, a 500cc triple introduced in 1969 that stunned the motorcycling world with its explosive power-to-weight ratio. However, the H1’s notorious handling and abrupt power delivery made it both feared and revered. Kawasaki engineers, emboldened by its commercial success, began working on a larger-capacity version aimed squarely at the burgeoning American market, where quarter-mile times and top speed were primary sales drivers.

Kawasaki’s approach to the H2 was clear: to produce the fastest accelerating motorcycle available. It was not designed with refinement in mind. Instead, it was a blunt-force instrument, conceived in the pre-emissions regulation era when noise, smoke, and fuel economy were secondary to outright performance.

Technical Specifications

The Kawasaki H2 Mach IV featured an air-cooled 748cc inline three-cylinder engine with a 120-degree firing interval and piston port induction. The engine had a bore and stroke of 71.0 mm x 63.0 mm and utilised a trio of Mikuni VM30SC carburettors. The compression ratio was 7.0:1, producing a claimed 74 horsepower at 6,800 rpm — a remarkable figure for a two-stroke of the era.

The bike’s weight was relatively modest at approximately 205 kg (dry), giving it a phenomenal power-to-weight ratio. Acceleration was staggering: 0 to 60 mph in around 4 seconds and a standing quarter-mile in 12 seconds flat, making it the fastest production motorcycle in 1972.

Top speed was roughly 126 mph (203 km/h).

Ignition was handled by a Capacitor Discharge Ignition (CDI) system, a pioneering choice at the time, delivering consistent spark and aiding in the high-revving engine’s performance. Lubrication was provided via Kawasaki’s improved Superlube oil injection system, which allowed precise oil metering without requiring premix, a key user-friendly upgrade.

Chassis and Handling

The H2’s double-cradle steel frame was lightweight but flex-prone, and suspension was basic: conventional telescopic front forks and dual rear shocks. Braking was via a single disc at the front and a drum at the rear, which proved barely adequate for the power on tap. Cornering stability and high-speed handling were secondary considerations, and the chassis often struggled to contain the engine’s ferocity.

Indeed, the H2 developed a reputation as a "widowmaker" — not entirely undeserved. Sudden, peaky power delivery and chassis flex could overwhelm riders who lacked experience or finesse. Kawasaki later made incremental improvements, including changes to frame geometry and the addition of steering dampers, but the H2 never lost its wild personality.

Evolution and Legacy

The H2 Mach IV was produced from 1972 to 1975, with updates to each model year. The 1973 H2A received minor cosmetic changes and refinements to ignition timing. The 1974 H2B introduced redesigned bodywork, oil injection system upgrades, and slightly softer power delivery. The final iteration, the H2C in 1975, featured continued emissions tweaks and revised porting to improve rideability and meet tightening noise and pollution standards.

Despite these changes, the H2's core identity remained: a no-compromise performance machine. It never attempted to challenge the four-cylinder Hondas and Suzukis on civility or long-distance comfort. Instead, it carved its place in history as a brutal, visceral machine built purely for speed and adrenaline.

End of an Era

By the mid-1970s, tightening environmental regulations, rising fuel costs, and changing consumer preferences marked the decline of large-capacity two-strokes. Kawasaki phased out the H2 in favour of four-stroke models like the Z1, which could deliver comparable performance with better refinement, fuel economy, and emissions compliance.

Nevertheless, the H2 triple left an indelible mark on motorcycling. It remains one of the most iconic two-stroke motorcycles ever built, celebrated for its audacity, mechanical simplicity, and raw acceleration. Modern collectors prize it highly, and its spiritual successor — the supercharged four-stroke Kawasaki Ninja H2 — pays homage in both name and purpose.

The original Kawasaki 750 triple exemplified an era when performance reigned supreme and engineering boundaries were pushed without compromise — a machine that earned its place not only on the drag strip, but in the pantheon of motorcycling legends.