Kawasaki H2 750

The orig­i­nal fe­ro­cious stro­ker

Practical Sportsbikes (UK) - - Wecome Part 1 -

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

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