Kawasaki H2 750
Two-Stroke Triple
With Ian Falloon
When Kawasaki released the H1 500 cc two-stroke triple in 1968 they showed they were prepared to go beyond traditional boundaries in the quest for performance. While Honda and Yamaha were concentrating on big four-strokes, Kawasaki maintained their faith in the two-stroke.
Two-strokes were cheaper to manufacture, produced much more horsepower per litre, and while they were thirsty, fuel consumption wasn’t an issue in the late 1960s. The H1 also offered unmatched performance for the dollar. When the H1 grew to 750 cc during 1971 and became the H2, for lovers of high performance two-strokes it was simply more of a good thing.
Generally known as the Mach IV, the H2 was a scaled-up version of the H1, but while the design of the piston-port triple was similar, everything was stronger. The 750’s port timing was also milder to create a broader torque curve. With a compression ratio of 7:1 and three Mikuni VM30SC carburettors the 71 x 63 mm two-stroke produced 74 horsepower at 6800 rpm.
This may not sound much for a 750 today, but back in the early 1970s most 750s barely made 60 horsepower and the closest to the H2 was the vastly heavier Honda CB750 with 67 horsepower. While the crank and port timing made for smoother running, the H2 was an extremely thirsty beast, soon earning a reputation as ‘petrol-cooled’.
Also ground-breaking for the time was the CDI ignition system. Powered by a crankshaft-mounted generator rather than a battery, each cylinder had an individual trigger, amplifier and coil.
Although the frame and running gear was also similar to the H1, the mild steel frame had additional bracing and the front brake was a single 296 mm disc with twin-piston caliper. This was a far superior unit to the drum brake of the earlier H1, but the H2 was still afflicted with the skinny forks and limp shock absorbers that were universal on Japanese motorcycles at that time.
The weight was a very moderate 192 kg and when it came to performance there was absolutely nothing that could touch an H2 in 1972, and even 1973. In Cycle magazine’s seminal 1973 Superbike comparison test the H2 demolished a field that included Kawasaki’s own Z1, Honda CB750, Ducati 750 GT, Norton Commando 750 Combat, Triumph 750 Trident and Harley-Davidson Sportster.
The H2 produced the most rear wheel power, most stopping force (0.922 G), quickest quarter mile and track lap time, and was significantly cheaper. The top speed was in excess of 200 km/h, if you could hold on to the high handlebars and control the weaving.
High-speed stability wasn’t a strong suit and riding one of these early H2s at high speed required strength and determination. As Cycle magazine editor Cook Neilson told me, “The H2 nearly killed me on our favourite test road in the Santa Monica mountains when I ran off the road and ended up in a fence.”
Despite deficiencies the H2 was a formidable production racer. A H2 ridden by Mike Steele and Dave Burgess won the 1972 Castrol Six-Hour production race.
In New Zealand H2s ridden by Alan Collison and Owen Galbraith were almost unbeatable until 1975, particularly on short street circuits where their combination of moderate weight and excellent acceleration was ideal.
The early H2A was arguably the definitive model. Unlike today, where new models provide an improvement over their predecessor, this wasn’t the case in the early 1970s. While gradual evolution saw changes in styling and improvement in handling, they were complemented by a reduction in engine performance to meet more stringent noise and emission requirements.
By 1974, the H2B was more stable (thanks to a longer swingarm), but was heavier. For the H2C of 1975, the power was reduced to 71 horsepower at 6800 rpm and the weight had climbed to 208 kg. The days when the H2 was the performance king were now over.
The H2 was a victim not only of the 1974 Middle East fuel crisis but also Kawasaki’s own four-stroke Z1. Four-strokes were more fuel efficient and environmentally friendly, and by 1976 they were much faster than any production two-stroke.
Now the H2 is a remnant of another age. H2s were all about engine performance, with handling secondary, and convenience features such as an electric start noticeably absent. Despite its superior performance, even in 1973 the H2 wasn’t a mainstream Superbike and was never as popular as a CB750 or Z1.
Now they are cult machines for those who appreciate the era of two-stroke dominance. Compared to an early H2, four-stroke Japanese Superbikes were simply bland and boring…
1972 Kawasaki H2 Specifications
| 1972 Kawasaki H2 Specifications | |
| Engine | Air-cooled, two-stroke, tranverse three-cylinder, 748 cc |
| Bore x Stroke | 71 x 63 mm |
| Compression Ratio | 7.1:1 |
| Induction | Three Mikuni 30 mm VM30SC carbs |
| Power | 74 hp (55 kW) @ 6800 rpm |
| Torque | 77.4 Nm @ 6500 rpm |
| Gearbox | Five-speed |
| Clutch | Wet, multi-plate |
| Frame | Tubular double cradle |
| Front Suspension | Telescopic forks |
| Rear Suspension | Two shocks, adjustable preload |
| Brakes | 295 mm front rotor, two-piston caliper, 203 mm rear drum brake |
| Tyres | 2.25 x 19 inch, 4.00 x 18 inch |
| Wheelbase | 1410 mm |
| Seat Height | 795 mm |
| Weight | 192 kg (dry) |
