Kawasaki H2 750
Two-Stroke Triple
With Ian Falloon
When Kawasaki launched the H1 500 cc two-stroke triple in 1968 they confirmed they have been ready to transcend conventional boundaries within the quest for efficiency. Whereas Honda and Yamaha have been concentrating on large four-strokes, Kawasaki maintained their religion within the two-stroke.
Two-strokes have been cheaper to fabricate, produced way more horsepower per litre, and whereas they have been thirsty, gasoline consumption wasn’t a problem within the late Sixties. The H1 additionally provided unmatched efficiency for the greenback. When the H1 grew to 750 cc throughout 1971 and have become the H2, for lovers of excessive efficiency two-strokes it was merely extra of a very good factor.
Generally called the Mach IV, the H2 was a scaled-up model of the H1, however whereas the design of the piston-port triple was related, the whole lot was stronger. The 750’s port timing was additionally milder to create a broader torque curve. With a compression ratio of seven:1 and three Mikuni VM30SC carburettors the 71 x 63 mm two-stroke produced 74 horsepower at 6800 rpm.
This will not sound a lot for a 750 right this moment, however again within the early Nineteen Seventies most 750s barely made 60 horsepower and the closest to the H2 was the vastly heavier Honda CB750 with 67 horsepower. Whereas the crank and port timing made for smoother operating, the H2 was a particularly thirsty beast, quickly incomes a fame as ‘petrol-cooled’.
Additionally ground-breaking for the time was the CDI ignition system. Powered by a crankshaft-mounted generator fairly than a battery, every cylinder had a person set off, amplifier and coil.
Though the body and operating gear was additionally much like the H1, the gentle metal body had further bracing and the entrance brake was a single 296 mm disc with twin-piston caliper. This was a far superior unit to the drum brake of the sooner H1, however the H2 was nonetheless bothered with the thin forks and limp shock absorbers that have been common on Japanese bikes at the moment.
The load was a really reasonable 192 kg and when it got here to efficiency there was completely nothing that would contact an H2 in 1972, and even 1973. In Cycle journal’s seminal 1973 Superbike comparability check the H2 demolished a discipline that included Kawasaki’s personal Z1, Honda CB750, Ducati 750 GT, Norton Commando 750 Fight, Triumph 750 Trident and Harley-Davidson Sportster.
The H2 produced probably the most rear wheel energy, most stopping drive (0.922 G), quickest quarter mile and observe lap time, and was considerably cheaper. The highest pace was in extra of 200 km/h, when you may maintain on to the excessive handlebars and management the weaving.
Excessive-speed stability wasn’t a powerful swimsuit and using one in all these early H2s at excessive pace required power and willpower. As Cycle journal editor Prepare dinner Neilson informed me, “The H2 practically killed me on our favorite check highway within the Santa Monica mountains after I ran off the highway and ended up in a fence.”
Regardless of deficiencies the H2 was a formidable manufacturing racer. A H2 ridden by Mike Steele and Dave Burgess received the 1972 Castrol Six-Hour manufacturing race.
In New Zealand H2s ridden by Alan Collison and Owen Galbraith have been virtually unbeatable till 1975, notably on brief road circuits the place their mixture of reasonable weight and glorious acceleration was best.
The early H2A was arguably the definitive mannequin. Not like right this moment, the place new fashions present an enchancment over their predecessor, this wasn’t the case within the early Nineteen Seventies. Whereas gradual evolution noticed modifications in styling and enchancment in dealing with, they have been complemented by a discount in engine efficiency to fulfill extra stringent noise and emission necessities.
By 1974, the H2B was extra secure (because of an extended swingarm), however was heavier. For the H2C of 1975, the ability was lowered to 71 horsepower at 6800 rpm and the load had climbed to 208 kg. The times when the H2 was the efficiency king have been now over.
The H2 was a sufferer not solely of the 1974 Center East gasoline disaster but additionally Kawasaki’s personal four-stroke Z1. 4-strokes have been extra gasoline environment friendly and environmentally pleasant, and by 1976 they have been a lot quicker than any manufacturing two-stroke.
Now the H2 is a remnant of one other age. H2s have been all about engine efficiency, with dealing with secondary, and comfort options akin to an electrical begin noticeably absent. Regardless of its superior efficiency, even in 1973 the H2 wasn’t a mainstream Superbike and was by no means as standard as a CB750 or Z1.
Now they’re cult machines for individuals who admire the period of two-stroke dominance. In comparison with an early H2, four-stroke Japanese Superbikes have been merely bland and boring…
1972 Kawasaki H2 Specs
| 1972 Kawasaki H2 Specs | |
| 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 |
| Energy | 74 hp (55 kW) @ 6800 rpm |
| Torque | 77.4 Nm @ 6500 rpm |
| Gearbox | 5-speed |
| Clutch | Moist, multi-plate |
| Body | Tubular double cradle |
| Entrance Suspension | Telescopic forks |
| Rear Suspension | Two shocks, adjustable preload |
| Brakes | 295 mm entrance rotor, two-piston caliper, 203 mm rear drum brake |
| Tyres | 2.25 x 19 inch, 4.00 x 18 inch |
| Wheelbase | 1410 mm |
| Seat Top | 795 mm |
| Weight | 192 kg (dry) |
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