The 500cc Kawasaki H1 Triple - CLASSICS REMEMBERED

Technical Editor Kevin Cameron takes a look back at the classic motorcycles of yesterday

Kawasaki H1 Mach III static side view
1969 Kawasaki 500 H1 Mach IIIMike Schinkel derivative work: Ligabo via Wikimedia Commons

The most striking thing about a 120-degree-firing triple is its musical exhaust sound. I heard it for the first time at the old Loudon, NH track when Kawasaki people briefly demonstrated their new bike, released in 1969. The weeklies (Remember them? Printed on actual paper?) had speculated in learned fashion, trying to relate Kawasaki's coming air-cooled Triple to the DKW 350 racer of the mid-1950s. Naturally, the big drawback of three cylinders in-line is width, so DKW had laid its center cylinder just below horizontal with the outer pair nearly upright, thereby being able to narrow their engine by about two inches.

When the Kawasaki appeared at 60 x 58.8-mm bore & stroke, it was completely straightforward – three cylinders in-line, with a tall alternator/ignition cover adding inches of width on the left, and with its gear primary drive to a 5-speed gearbox on the right. The keynote of Kawasaki's design was to price this model to sell in serious numbers. That meant giving up fancy stuff such as the rotary intake valves of their previous A1/A7 twins in favor of the maximum simplicity of piston-controlled intake ports. Also, no staggered cylinders such as adopted by Suzuki in 1972, and no complicated gear-driven piggy-back alternator as on A1/A7.

Because of these production economies, the H1 provided maximum bang-for-the-buck. Go ahead and throw those hi-comp pistons into your BSA Super Rocket! Cam your Sporty til its valves thunk the pistons! Build your Triumph straight from the JoMo booklet! When you’re done, it’s still just a wheezing old four-stroke – suck/wheeze/pop/chuff/repeat.

Kawasaki H1 Mach III 500cc engine close-up
Kawasaki H1 Mach III 500cc enginesadicarno Bridge Boy at en.wikipedia, via Wikimedia Commons

Kawasaki’s regional service manager showed everyone how to humble the mighty. With engine running and in-gear, stand over the bike, weight on your feet. Rev it, dump the clutch to spin the tire, and sit down. Super Rockets became smoke-obscured dots in your mirrors.

Out the doors of our dealership they flew, and some of our riders joined the wee hours hunter groups, looking for four-strokes whose owners still thought they were fast. Working on our own projects, we were often at the shop past closing, and H1 men dropped in to tell their tales of midnight smoke and conflict. Their hyped-up enthusiasm brought to mind the famous WW II photo of carrier pilots enthusiastically re-enacting (with their hands) a successful air strike.

Like all crankcase-scavenged two-strokes, the H1 had an all-rolling-bearing crankshaft with six main ball bearings and four seals. These were modern times, so there was no messy mixing of oil and gas; a tiny three-outlet metering pump, located above the crank’s primary pinion, varied the oil supply from a small tank to each cylinder according to throttle opening. Because our industry is always thinking about warranty, these pumps were factory-set to lay heavy smoke on full throttle. As we accumulated experience, we were able to notch this back considerably.

Kawasaki H1 on the April 1969 cover
Kawasaki H1 on April 1969 cover of Cycle WorldCycle World

Oil was supplied to three crankcase drillings, each supplying oil to one main bearing of each cylinder. On the crank wheel facing this bearing was screwed an oil pick-up ring with rubber lips. The oil it collected from the main bearing’s overflow entered one end of that cylinder’s drilled crankpin, emerging through a radial hole in the center of the con-rod’s big-end needle bearing roller track at TDC. Because this resulted in flaking at the oil hole edges, we changed this (in crank rebuilds)to 30-deg BTDC and there was no more flaking.

We had no problems with this system, and when seized bikes came in or trucks or trailers, their oil tanks were always full to the top. Warranty games.

One customer was very busy with his expanding empire of hi-fi stores, so every spring he’d phone and ask us to come get his bike, chained to a parking meter, out of the snowbank in which it had spent the winter. After inspection, we’d inform him that extensive rusting had created a need for a new crank plus re-bores and oversize pistons on all three cylinders.

“Send me the bill.”

Kawasaki H1 magazine layout from April 1969
Kawasaki H1 Road Test from the April 1969 issue of Cycle WorldCycle World

I would be given for rebuild many a crank with the flywheels of one or more cylinders showing an actual water line. But I also had one exemplary customer who used his bike mainly for impatient dashes up and down the Maine Turnpike at 100-mph to his summer place. His was a very early bike and it had 50,000 miles of this high speed use when its crank came to me. It was worn but still usable – I was impressed. Better by far to spend your life at 100-mph, which means hot enough that liquid water (and therefore rusting) cannot exist within – than to stand out in New England rain, waiting for the owner’s occasional two-up trips to the Cape. This was a big point in Ford’s late 1980s experimental program to evaluate possible two-stroke powerplants for economy cars – how do you keep rust out of crankcase-scavenged engines?

Inevitably, there came the talk that "That center cylinder there, she runs real hot." That was not our experience; a properly set up engine ran fine on all three. And on the H1-R road racer, the center cylinder always ended up jetted leaner than the outers. Why? 120-degree Triples don't shake vertically, but they do have a strong rocking couple. In fact, the crank moves just like a double-bladed kayak paddle. That means that its center cylinder pretty much sits still, while the #1 and #3 cylinders whip around in orbits. That, by somewhat frothing the fuel in their carb float bowls, made them run a couple of jet sizes leaner than the center.

Kawasaki H1 story magazine layout
Kawasaki H1 story from July 1986 issue of Cycle WorldCycle World

Because the H1 engine and chassis were fairly heavy in relation to piston mass, this vibration was not intolerable. But when the Kenny Roberts Team built their Proton Triple (also a 500) it was quite light so its rocking couple moved it around a lot more. Parts broke and carburetion was bolluxed. Eventually, Honda's grumpy Yoichi Oguma offered to redesign the engine with a balance shaft to cancel the rocking couple, civilization reigned, and the bike began to show some promise just as the 500-cc formula was ending.

The Japanese market version of H1 (and the initial H1-R of 1970) had coil-and-battery contact-breaker-triggered ignition, but the US market received CDI versions. High voltage doesn’t like to stay where you want it, but is always sparking or forming corona or some other trouble. And so there was a snowfall of service bulletins and ignition updates. This was the era in which engineers were determined to show that the old two-stroke bugaboo – plug fouling – could be magically ended by technology. After a while, this madness settled down as racing CDIs (such as the Spanish Femsa of 1969 or the German Krober), implemented with a couple of bucks-worth of radio quality parts, turned out to work just fine even though they didn’t require NGK’s “staring eye” BUHX surface-gap spark plugs or plug wires originally designed for high-energy physics uses. Yes, aircraft magnetos for flight at 40,000-ft had to be pressurized to prevent corona loss, and there was even the far-out fix of filling magnetos and distributors with sulfur hexafluoride gas. Saner heads prevailed.

H1 quickly acquired the reputation of evil handling. A simple test usually isolated the cause. Remove the rear suspension units, pop off their springs and stroke the dampers up and down to see if there is equal damping. In some cases, a stock damper could lose its oil in a few miles. But the reputation persists, as if the H1’s chassis was not a technical construction, but rather a magically disloyal Excaliber which attacked its user. Yes, engines in that era were mounted far back, and yes, wheelies were easy with H1 power (We sold a lot of tail light lenses). But there was plenty of steel in the chassis and a pair of Konis or Girlings made a rideable suspension package. Worst condition was surely one damper working and the other empty of damper oil.

Some of our customers hurt themselves on their H1s, causing a friend of mine to tell me we were violating basic human morality by selling such machines to less than top expert riders. Was he right? In 1972 came the 50% larger displacement 750 H2, and in 1973 came ZI, 20% bigger again. This was a time of fascination with production vehicle high performance. Remember the Ford ‘Thunderbolt’ of 1964? Here, let’s drop this 600-hp 427 into this light mid-sized car. What’ll she do?

In recent years Japanese collectors have developed a particular taste for H-series machines, boosting the value of even “get runnings”. In the end, the actual qualities of fabled machines become unimportant in comparison with their legends.