Custom-Built Five-Cylinder Kawasaki Motorcycles

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Clive Adams’ 850cc five-cylinder H1 (front) and its 1,250cc five-cylinder H2-based big brother (rear).
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Fabricator Allen Millyard blends two Kawi triples together to make a five-cylinder engine.

Back in 1998, I read an article about British engine fabricator Allen Millyard’s wild Kawasaki multis, including a 250cc three-cylinder S1 made into a 444cc five and a three-cylinder KH400 made into a 666cc five.

Allen works as a mechanical engineer in atomic weapons research, so building motorcycles is like child’s play to him. At age 11 he put an Austin Mini car engine into a BSA Bantam frame to run around the waste land near his house. Not an ideal match, but it was all he had.

I was captivated, so I phoned Allen and asked about making one based on a 500cc or 750cc machine. Allen had made Kawasaki two-stroke triples into four, five and six-cylinder machines; he recommended a four as the best rider and a five as the best show bike.

At first I was going for an Kawasaki H2, but after seeing a photograph of a 1969 Kawasaki H1 and a 1972 H2 side-by-side, I decided I preferred the old school look of a first series H1 best. A former co-worker, Al Howker, had two early H1s. He also had a 1971 parts bike. For $700 I purchased both bikes, then dismantled them, crated them and sent them to Allen in England.

The project was very much a partnership. As an airline captain, I could arrange trips to London and work on the bike on my layovers. I was in charge of getting all the paintwork, chrome plating, powder coating, nickel plating, upholstery, and replacement and replica parts. Allen is an engineer, not a restorer.

The bike was finished in 1999, and made an appearance at the Classic Mechanics Show at Stafford, where Allen was preparing the engine for my next bike, the mighty 1,250cc five-cylinder 1973 H2 I had commissioned. He actually built the engine during the show. Later, the bike returned to the United States where it joined my collection.

At the risk of sounding facetious, it rides just as you’d expect a 1970 H1 with five cylinders would. It has a larger front and smaller rear sprocket so the engine runs in the torque section of the power curve rather than in the revs section. This gives it a “Gentlemen’s Express” feeling rather than an “Adolescent Rush.” It is a lot smoother than a standard machine, with power pulses coming every 72 degrees opposed to every 120.

The Kawasaki fours and fives were Allen’s only attempt at serving the paying public. He’s made about 30 machines, with customers in Japan, the United States, France and England. Type certification stopped most customers from importing them. My 1970 H1 500 was the first one ever made as an 850cc five. He also turned a 1969 and 1972 H1 into 680cc four-cylinder machines.

I have ridden a five-cylinder 850cc Kawasaki KH500 at the Isle of Man TT circuit. That machine is now with the Barber Museum in Birmingham, Ala. George Barber also owns Allen’s 1,600cc V8 1974 Kawasaki Z1. Allen also made a 2,600cc V12 from a 1979 Kawasaki KZ1300. All because somebody said it was impossible.

Read more about the motorcycle mentioned in this article:
Kawasaki H2 Mach IV
1970 Kawasaki H1 Mach III1973 Kawasaki Z1 
Benelli Sei 900 vs. Honda CBX 1000 vs. Kawasaki KZ1300

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