Kawasaki H2 Mach IV

Fast, loud, rude and a little unstable, the Kawasaki H2 Mach IV was a rebel in its time. Today it’s a prized motoring heirloom.

profile rear view of Kawasaki H2 Mach IV

The H2 could go 0 to 60mph comes in a blistering 4.1 seconds.

Photo by Robert Smith

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Kawasaki H2 Mach IV
Years produced:
Total production: N/A
Claimed power: 74hp @ 6,800rpm
Top speed: 120mph (period test)
Engine type: 748cc
Weight (dry): 205kg (450lb)
Price then: $1,386
Price now: $3,000-$4,500
MPG: 18-28

The bugs are out in force today, I’m thinking, as I follow Dave Gurry’s 1972 Kawasaki H2 Mach IV 750 along the back lanes of southwest British Columbia. Then I realize the spots on my visor aren’t bugs, they’re oil droplets carried in the blue haze that accompanies the big stroker wherever it goes.

Admittedly, Dave has “improved” the Kawasaki’s automatic lubrication system to allow extra oil into the engine. “I’d rather burn a little more oil than seize a piston,” he says. And given the price and availability of replacement parts should a blow-up occur inside the piston-port engine, Dave’s logic is impeccable.

Read Dave Gurry's review of owning and riding the 1972 Kawasaki H2 Mach IV 750 

Then again, anti-social behavior was part of the H2’s ethos. Designed for straight-shot performance in traffic signal drag races, power was paramount; everything else — noise, pollution, fuel consumption — was an afterthought.

The H2 had “only one purpose in life,” according to Kawasaki’s 1972 sales brochure — “To give you the most exciting and exhilarating performance.” It also mentioned how the H2 “demands the razor sharp reactions of an experienced rider,” and is “a machine you must take seriously.”

Seriously, indeed. Consider: Seventy-four explosive horsepower stuffed into a powerband only 2,800rpm wide; a frame better suited to a moped; fuel consumption that would drop below 20 miles per gallon; spark plugs that fouled in less than 10 minutes of city riding; and all this accompanied by clouds of blue smoke and the raucous ring-a-ding racket of a big air-cooled multi-cylinder two-stroke.

The motorcycling equivalent of the Sex Pistols, the Kawasaki H2 Mach IV 750 stuck its middle finger firmly in the face of respectability when it burst onto the road in 1972. Essentially a scaled-up version of the Kawasaki H1 Mach III triple, with equally evil handling and similarly violent performance, the Mach IV was, in the hands of an inexperienced rider, an accident waiting to happen.

“Admiring it from a distance was safer than climbing aboard,” wrote Mac McDiarmid in his book Classic Superbikes. “The big Kawasaki’s uncompromising nature would quite possibly be outlawed today.”

Tracing the Triples

1972 was a banner year for quick bikes, and 750cc was the class to be in — not least because of the popularity of Formula 750 racing. Norton released the Combat version of its award-winning Commando with over 120mph on tap, MV Agusta had announced its 750S a year before, the Suzuki GT750 was soon to be in the showrooms, the Moto Guzzi V7 Sport was launched and Paul Smart won the Imola 200 on the brand new Ducati 750SS.

Kawasaki’s contribution to the need for speed employed technology it already understood. Strokers were its bread and butter, and the 1972 H2 Mach IV owes much to the three-cylinder H1. Producing 60hp at 7,500rpm (with precious little power below those revs) and weighing only 410lb, the H1 became the benchmark for outrageous street performance. With the proliferation of 750cc Superbikes, Kawasaki was spurred to up the ante. Though it had originally planned the H2 as a 650, the 750cc imperative made the extra cubes an easy choice, and may explain why the H2 engine has somewhat more “oversquare” dimensions than the 500.

Instead of the disc- and reed-valve two-stroke designs then coming on to the market, Kawasaki stuck to a piston-port design for simplicity and compactness. Its 70mm diameter pistons topped a 62mm stroke, with a 120-degree crankshaft running on six main bearings. Three Mikuni 32mm carburetors provided the fuel-oil-air mixture (a pump fed oil to each carburetor float bowl as well as to the crankshaft), and a Mitsubishi capacitive discharge ignition system provided the sparks.

Launched in late 1971, the 750cc H2 weighed just 40lb more than the 500cc H1, yet produced a class-leading 74 crankshaft horsepower at 6,800rpm. By comparison, its closest power rival in the 750 field, the Triumph Trident, could claim only around 58hp. The H2 had another significant advantage over its rivals: At under $1,400 — including the 10 percent import duty then in force — it was $300 cheaper than either the Honda CB750 or the Norton Commando Roadster, and $430 cheaper than the Trident.

In spite of the wide-ranging skills that must have been available within the Kawasaki Heavy Industries group, motorcycle frame design did not seem high on their list of capabilities. The H2’s lightweight tubular cradle was incapable of containing the vicious thrust of the peaky stroker. The frame flexed under cornering, while any surface irregularity at speed would destabilize the front wheel, causing a disconcerting weave, and making precise positioning on the road something of a gamble. The H2’s weight was also biased toward the rear, which, combined with a short swingarm, caused the front wheel to lift under acceleration if the rider was unprepared.

However, in the hands of a competent pilot, the H2 could be made to perform extremely well. In a 1973 Cycle seven-bike shootout, the H2 was awarded top rating, especially in terms of value for money, beating every other contender on performance except its own erstwhile successor, the 903cc four-stroke Kawasaki Z1.

In 1973, Kawasaki made a small number of mainly cosmetic changes, including a chrome front fender instead of the 1972 painted item. For 1974, the H2 saw numerous engineering changes, including porting revisions and a longer swingarm to tame the peaky power delivery, improve fuel consumption and stabilize the handling. But time was running out for big strokers: they simply couldn’t meet new emission regulations without significant added expense. The new realities of the mid-1970s — oil crises, safety, environmental and noise regulations — put the H2 in the same position as Richard Nixon. They both had to go.

But Kawasaki was ready with a winner in the wings: In 1973, the company trumped its own ace with the 900cc DOHC four-stroke Zl. And the rest, as far as high-performance Kawasakis are concerned, is a recent, but very rich, history. MC 

Press Reports

“As expected, the Mach IV is an absolute jet, leaves all sorts of rubber on the pavement, pulls strongly in every gear, and shows absolutely no lag as you click your way from first to fifth.”
Cycle World, November 1971

“Like its predecessor, the Mach III, the new 750 Mach IV is a rocket. The only drawback is that getting to the moon first, or to the next tavern as the case may be, costs money. If your daddy has a gas station and your uncle owns a tire store you’ll be better off than most Mach IV owners. If not, the local gas pump jockey will be on a first name basis with you and the tire man will call you up on your birthday.”
Cycle, December 1971

“The Mach IV rates as the ultimate stud bike right now available in terms of raw power and sheer speed, although it does lack the refinement of some strictly touring machines. If being the fastest on your block appeals to you, so will the Mach IV!”
Cycle World, March 1972

“The Kawasaki H2B is perhaps the best remaining example of the superbike concept — where performance is paramount and very little interferes with it. Its superbike character is manifested in its engine, which has more power and performance than any other 750 street machine.”
Cycle Guide, September 1974

“Without a doubt, Kawasaki’s awesome 750 Triple is a bike that has outlived its usefulness. It was conceived at a time when the buying public was preoccupied with acceleration. Gut-grabbing acceleration. And little else. And the bike delivered to the tune of mid-12-second quarter-miles and wheelies that would stop your heart.”
Cycle World, March 1975

“Time has dictated that a change is due. Perhaps overdue. And in a way that’s sad because brute power machines like the H2 turned a lot of people on at a time when all of us could afford to be carefree.”
Cycle World, March 1975

Read more about the motorcycles mentioned in this article: 

1970 Kawasaki H1 Mach III  
Suzuki GT750 
Moto Guzzi V7 Sport 
1968 Triumph Trident T150
Honda CB750: A Classic for the Masses 
1973 Kawasaki Z1: King of the Road 

6/22/2015 9:22:23 PM

this bike was one of the all time best owned one for many years.As for being not safe thats bunk my bike could corner with no flex in the frame whatsoever with a matched set of perrellis on it and roller bearings in the swing arm instead of bushings it was great . i had the 74 which was 4 inchs longer then the 72 and 73 wiseco pistons bill wereges expansion chambers it was fast indeed had a lot of fun on that bike they were great indeed

paddy johnson
7/17/2012 5:49:39 PM

The bike's frame was a wee bit flexible. Eventually, I learned to accelerate in to corners to allow the chain firm up the bike. Paddy

5/14/2012 7:30:50 PM

As the owner of an 72 H-2 in 1974,I can attest to its wheelstanding tendencies whether deliberate or not.I guess the only reason I never had an accident was my extreme fear of this bikes tendency to stand up on its pretty blue tailet.Never had a problem with fowled plugs in the 15000 miles I put on it probably due to the 73 carbs my dealer installed.I have had many bikes since like a 73 Z-1,79 CBX and an 82 CBX that I rode all over the eastern half of the US.Not one of the bikes I had rode since have put such a healthy fear of getting hit on my chin by the instrument cluster as the bike tried to shoot out from underneath me!

lynn davidson
8/30/2011 8:05:01 PM

Unless you have some serious saddle time on big muscle bikes (or pissed off Brahma bulls) stay off this bike. This is an unapologetic slingshot with a narrow but frightening power band that will sneak up on you, and when it comes in to that narrow band as far as I know there is still nothing street legal even today that will better it, it's a straight line missile up to around 120 THAT CAN AND WILL KILL YOU! Notorious for high speed wobble and inadequate brakes it's the equivalent of a Yugo with a 454 rat engine. I've ridden my buddy's 03 Hayabusa, and it would eat the ol H2 up without a belch, BUT NOT IN THAT LITTLE TACH WEDGE WHERE MOST OF THE NUCLEAR FISSION TAKES PLACE!I almost never took it out without getting some kind of rush before I got back home. If there's any such thing as a legend among notorious bikes, this is it! I sold it many moons ago, but it was quite an experience.

lynn davidson
8/30/2011 2:24:51 AM

I had for about two years or so, a love/hate relationship with an over performing under engineered "750 widowmaker". I first rode it just to try it out for a friend. He found it in the classifieds and we went together to check it out, and while he rode it I stood around and talked to the owner, who said he was selling it because he wasn't prepared at the time to die! My friend was only gone for perhaps five minutes or so, and when he came back in he looked at me a little unsteadily, shaking his head he said not for me, you want to try it? At the time we were both riding 750 Honda's which were in their day a quite respectable performer so I said yeah what the hell, can't be that mean. Wrong. So I wheeled it out onto the roadway and fortunately (luckily) I resisted the impulse to roll the throttle on as fast as I normally might have and just gave it ample time to wind up to about third gear, then I kicked it in the ass and was rewarded by about five or six seconds of pure terror trying so hard to stay on the damn thing I couldn't release the throttle till I got my grip and seating re-established, by then I as coming into a forty mile per hour right hand curve at probably seventy or more with a pickup truck coming in the opposite direction. When I tried to lay the thing over it threatened to go squirrelly and I had no choice but to swing out in the other lane. The only reason I missed the truck was he was quick thinking enough to go off the pavement to avoid me. Great ol bike.

3/3/2010 1:09:56 PM

My brother and I had these bikes and at the time it was King of the road. We took them to Daytona for bike week and I was never beaten by any other bike. They vibrated like HELL but were very fast. Smoked like a Thanksgiving Turkey but a LOT of fun! AWWWW those were the days. I am still riding.....but a little slower.

3/3/2010 1:08:52 PM

My brother and I had these bikes and at the time it was King of the road. We took them to Daytona for bike week and I was never beaten by any other bike. They vibrated like HELL but were very fast. Smoked like a Thanksgiving Turkey but a LOT of fun! AWWWW those were the days. I am still riding.....but a little slower.