Kawasaki had experimented with larger bikes with the 624 cc W1 twin, (a BSA A10 knock-off) in 1966, but then went back to the drawing board and came up with the H1 Mach III two-stroke triple of 1969.
Gracing the cover of both Cycle and Cycle World in April 1969, it offered 60 bhp from a three-cylinder two-stroke engine of 498 cc, weighed 382 lbs and could turn a quarter mile in 12.4 seconds on its way to a top speed of 124 mph. Honda’s game-changing 750 had been upstaged, and at $999 the Kawasaki was almost half the price of the Harley-Davidson’s XLH.
Not all of the statistics were positive, though. 57 percent of the bike’s weight was on the rear wheel, and the frame was constructed of small steel tubes that proved to be fairly weak. The drum brakes were also less than exemplary, and accelerating through a corner often generated a “tank slapper.” Even so, the Kawasaki H1 Mach III was incredibly exciting. Its exhaust let out a thrilling wail from its triple pipes, and dazzling pearl white and purple paint only added to the attention grabbing.
The Mach III was very thirsty, with a range of about 80 miles to a tank of fuel, and engine vibration could numb your fingers after a longer ride. Electrics, meanwhile were quite good with a capacitor discharge ignition providing enough spark to prevent plugs fouling, and a waterproof cover was added in 1970.
The sleek fuel tank was enlarged for 1971 and efforts were made to strengthen the frame. A long awaited front disc brake became available the following year. That same year Kawasaki added a 250 cc S1 Mach I triple and a 346 S2 Mach II triple. Completing the lineup was the king of the hill – the H2 Mach IV 748 cc triple, which was even faster and crazier than the 498 cc version.
Meanwhile, Honda’s 750 4-cylinder, 4-stroke lesson had not been lost on Kawasaki and the DOHC 900 cc Z1 was launched to great acclaim in February 1972. It would sell 80,000 units in the next two years and ultimately outlast the screaming 2-stroke triples.
The two-strokes continued their development, and 1974 saw the S2 250 cc triple joined by an enlarged S3 – now up to a 400 cc displacement and with square fins on the cylinders to differentiate it. The 498 cc Mach III H1E gained valves to direct oil to the main bearings, while the 748 cc H2B Mach IV received new bodywork and a long-overdue steering damper.
The year 1975 saw the Z-1 takeover the high performance mantle, as the Mach IV was discontinued, but the 498 cc Mach III would continue through 1976 and its 250 cc Mach I sibling unaccountably survive it by an extra year.
The early Kawasaki triples have understandably gained a following among collectors, and because their handling characteristics can best be described as unforgiving, the number of survivors is not particularly high. The excitement they offer, though, is sufficient payoff for a relatively high purchase price in the collector market.
As is often the case, it’s best to buy only bikes with long-term provenance and check carefully for accident damage repair, and it’s worth noting that some parts are hard to find and can be expensive. At the end of the day, this is one of the more memorable models from a formative period in Japanese motorcycles, it has a place in just about any bike collection.

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