Kawasaki H2 750
The original ferocious stroker
ADDING ONE EXTRA CYLINDER to a conventional two-pot two-stroke doesn’t sound like a big deal, but Kawasaki’s pioneering triples gave motorcyclists a fright as the 1970s began. The H1 ‘Mach III’ came first – a 60bhp, lightweight 500 that was a jump forward from lazy British twins and singles, and even the other early Japanese machinery starting to gain popularity.
The piston-ported, 120-degree firing order motor gave 750-class power, but also civility from the efficient induction and porting, as well as minimal vibration. Electronic ignition cut maintenance time, and the chassis was good for the period too.
But it was the savagery that earned it a reputation. Magazine testers deemed them suitable for very experienced riders only – advice borne out by the numbers crashed. Startled owners were introduced to involuntary power wheelies, and even wheelspin on the crummy tyre technology of the era.
So you can only imagine the effect of upscaling the idea by 50 per cent to create the H2 750 ‘Mach IV’ for 1972. Everything else on two wheels suddenly looked staid and sensible – and it was a long time before the H2 would be considered anything other than the most animalistic thing on two wheels. Want to buy one? We don’t blame you. Read on for the full back story, and every piece of information you need to go and buy your own two-stroke hooligan.
THE H2 WASN’T an advanced machine, even for 1972. The basic credentials are the same as the H1 introduced three years earlier, except the numbers in every spec box are bigger. Each aspect of the engine and chassis was scaled up accordingly for the extra 14bhp the H2 produced over its older 500cc sibling.
The advantage of three cylinders over two starts with port area. Two-stroke porting is limited by the cylinder wall area, always a compromise when you’re trying to build an engine for all purposes, and the larger the capacity of each cylinder, the more gas-flow and piston speed is compromised. Vibration also becomes a problem.
By spreading the capacity over more and smaller cylinders, you can have greater overall port area which ultimately gives more power. An added bonus is that the ignition and subsequent flame has a shorter distance to travel, so combustion is quicker and more efficient than that in a bigger-bore cylinder.
Kawasaki had already had successful experience with disc-valve induction, but packaging three rotary valves would result in unacceptable crankcase width, so the triples remained piston-ported.
Points ignition proved insufficient early on in development when asked to fire three cylinders with hundreds of sparks per second, so Kawasaki nicked capacitor-discharge ignition from the other Japanese manufacturers’ multi-cylinder GP bikes to deliver 25,000 volts to each plug every time.
Autolube was used to feed oil directly to the bottom-end, which uses labyrinth seals to separate each cylinder’s crankcase.
Kawasaki sought to minimise overall width on both the H1 and H2 engines, but an increase in dimensions for the H2 was inescapable so, to maintain cornering clearance, it’s an inch-and-a-half taller too.
The chassis is typical early 1970s Kawasaki – a steel double cradle, twin shocks, wire wheels and a single disc at the front, with an optional second disc at horrific expense.
Development was carried out in part by American drag racer Tony Nicosia, who was already using a H1 500 to great effect on the strip, so he was a logical choice for testing the bigger evolution of Kawasaki’s first triple.
Quarter-mile times were in the 12-second bracket with a terminal speed just over 100mph, and top speed was reached a short while later at a real 120mph, though the speedo would claim a great deal more.
Rick Brett has devoted most of his life to Kawasaki triples, chiefly the H2. He bought
“Few people would insure you on an H2 because of the bike’s reputation”
one of the first Uk-model machines in 1972, and since then has founded the Triples Club, set up his own parts and service operation, and spent years of his life trawling the junkyards of America to save bikes and parts to sustain H2 owners the world over. The information he’s gathered in the process is unrivalled – every H2 he has come into contact with is logged on his own database, and he now has more information on the H2 than Kawasaki does. He’s our expert for this feature, and still fondly remembers when the Mach IV came to the UK.
“I’ve always wondered why the H2 never sold well in the UK, but thinking back, the country was still recovering from WWII. Most young people couldn’t raise the cash to buy one outright, and HP was unheard of. If you wanted one on finance, your dad had to act as a guarantor, and they were of the generation that had to make every penny count – if you couldn’t afford it, you didn’t buy it, so there was no way they’d let you spend £754 on a bike.
“Insurance was a problem too – few people would insure you because of the reputation the bike earned. They really were hard to ride at the time – especially compared to Triumphs, Nortons and the sort of stuff we were used to, so plenty got crashed.”
‘Plenty’ is relative in this case. Kawasaki UK didn’t exist – the concessionaire was Agrati Sales in Nottingham, who ambitiously brought in 109 bikes in three batches in January, July and August 1972. They’d be selling the blue-only 1972 bikes well into 1973, when no more than 30 of the cosmetically changed H2A were shipped to the UK. In total, 8530 were built before production stopped in July 1973, and for reasons Rick has yet to identify, H2 production only recommenced in December with the first H2BS. Some 95 of these 1974 model-year bikes came to the UK from the 10,347 produced. Of the final 5009 officially built, we got only 120. In total, that’s just 355 bikes from 47,566 manufactured.
But that was enough. The H2’s reputation as a widow-maker was cemented early on – partly thanks to Kawasaki’s efforts to ensure the new machine would definitely get a lairy reputation. Rumours of the first-year production run being tuned aren’t quite correct, but Rick’s learnt the truth.
“They weren’t tuned, and still made the same power, but with every new model Kawasaki would ensure the press demonstrators were at their optimum – they’d be jetted and built to breathe at their best, so they were more lively.”
The H2’s four-year model run saw only cosmetic changes and minor refinements – the H2 lost none of the neck-snapping, wheel-hoisting power that made it such an object of desire.
There was nothing else like it – Suzuki built the GT750 ‘Kettle’ as a relaxed tourer, so comparison is unfair. This unique appeal died when the last bikes were sold in 1975. Kawasaki designed and built 20 prototypes for a liquid-cooled square-four successor, codenamed ‘Steak Tartare’ (a nod to the Z1 900, codenamed New York Steak).
But times had changed – a big two-stroke capable of drinking a gallon of fuel every 20 miles with a side helping of premium two-stroke oil was seen as folly as the oil crisis saw fuel prices rocket. The Z1 and its descendants were selling strongly anyway. The H2 had done what it needed to – established Kawasaki’s reputation for hairy-arsed motorcycles, so the square-four was abandoned along with the H2.
“The H2 established Kawasaki’s reputation for hairy-arsed motorcycles”
Early development bike with tamer styling
Kawasaki shop manual lays the simple H2 motor bare
Drag racer Tony Nicosia nails a pre-production H2