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.

| July/August 2006

  • Kawasaki H2 Mach IV engine
    The Kawasaki H2 is all attitude. Bold graphics, upswept triple pipes and cool tailpiece all speak to the bike's performance potential.
    Photo by Robert Smith
  • 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
  • rider on Kawasaki H2 Mach IV
    Considered a terror in its day, the H2 looks lean compared to today’s sport bikes and has aged well. While the H2’s reputation for poor handling was mostly deserved, it’s a reasonable machine at normal speeds.
    Photo by Robert Smith
  • Kawasaki H2 Mach IV engine
    Engine detail.
    Photo by Robert Smith
  • Kawasaki H2 Mach IV gas tank and gauges
    Bikes were equipped with a speedometer and tachometer.
    Photo by Robert Smith
  • profile front view of Kawasaki H2 Mach IV
    Parked and ready to tear up the road.
    Photo by Robert Smith

  • Kawasaki H2 Mach IV engine
  • profile rear view of Kawasaki H2 Mach IV
  • rider on Kawasaki H2 Mach IV
  • Kawasaki H2 Mach IV engine
  • Kawasaki H2 Mach IV gas tank and gauges
  • profile front view of Kawasaki H2 Mach IV

Kawasaki H2 Mach IV
Years produced:
1972-1975
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 

Charles of Perth
6/1/2019 12:49:55 AM

I had one of the very first sold in California.....Long time ago but I think it was late '71....The local Kawasaki d dealer was C.H. Wheat who was also a well-known US Kawasaki racer.....His son was a school-mate and we were good friends....I was in the USMC at the time this came out and I really wanted one so I told Chuck Wheat - CH's son....when they arrive I want one......Up till then we were both huge Kawasaki fans....I had before the H2, a Kawasaki 350 with after-market air-injectors.....Not sure of the horse-power (have to thank the guys at the March AFB metal shop for fitting them - don't tell their CO....).....Certainly well over 50hp.....It was leaving the Honda 450's for dead at the time....Anyway.....The H2 was the most amazing bike I have ever owned.....Much much more torque than the 350....It was pure adrenalin riding it.....the first hour....after that it got tedious with the vibration.....and the noise.....and the stops at the gas stations.....But for short trips and winding roads....unbeatable....I had issues within months with the motor mounts....and as luck would have it - my late brother was a super welder who did welding on dragsters etc.....He rewelded the lot and beefed them up considerably.....the welds were over twice as thick and never had a problem again....Now the war story.... I got sent to a base in Japan in early 72....My parents lived about 80 miles from Pendleton....so I asked my father to take care of it....He had never drove a motorcycle in his life.....and he was in his late 40's then....I slowly on weekends taught him how to drive the 'Widowmaker'.......And I left for Japan with him being able to ride it amazingly well. He knew how much power was there - and he drove it very conservatively. I instructed him to drive it at least once a month while I was gone....and he did....sometimes much more - because he like it....As luck would have it....Within a month of arriving in Japan - I got sent to Vietnam (mostly Bien Hoa) and was there until the ceasefire became obvious. I came back and my H2 was still in great condition - not a scratch - and my father was in love with it......Happy memories of the H2....I do think a lot about getting another one.....


william
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




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