In the mid-1960s the Japanese economy was experiencing a period of high economic growth and Kawasaki was looking to take advantage of it. The USA was the world’s biggest motorbike market at that time and riders were seeking larger bore machines with higher horsepower and higher top speeds. Kawasaki’s response was to put together a top secret project, referred to as the N100 Plan. Development got under way in earnest in July 1967 with the eventual target becoming a set of specifications that were nothing short of spectacular for the period: an engine capacity of 500cc, 60hp output (equivalent to 120hp per litre) and a standing quarter mile time of 13 seconds.
Kawasaki considered two different approaches to the construction of what would become the most powerful production motorcycle engine for its day. The first was to look at increasing the bore of the successful A7 to obtain a 500cc air-cooled two-stroke parallel twin cylinder rotary-disc valve engine.
The second approach involved the development of a revolutionary new engine layout, which went completely against the conventional wisdom of the day, building either a parallel or “L” design air cooled two-stroke three cylinder engine.
Both twin cylinder and three cylinder engines were developed alongside each other. The first thing to decide in the development of the triple was whether to use a parallel in-line layout or “L” cylinder layout to aid middle cylinder cooling. Kawasaki began experimenting with how best to cool the middle cylinder and the technical team prepared a mock-up of each engine which they took to the Faculty of Engineering at Osaka University. The results of these tests led to the conclusion that cooling efficiency would not be significantly impaired by arranging the cylinders in parallel and the company finally opted for the now familiar in-line triple cylinder layout.
At the same time, Kawasaki also pushed ahead with the development and testing of its twin cylinder rotary disc valve engine and the preliminary test results were very promising. However, once the layout of the three cylinder engine had been decided, the technical team concentrated all their efforts to the development of the two-stroke three cylinder piston valve engine that was ultimately to become legendary.
The technical team now turned their attention to the details, such as how to prevent the plugs from fouling at low speeds. It was difficult to obtain proper combustion at all engine speeds and the teams solution to this was to borrow from existing 2-stroke racing technology. Cutting edge CDI (Capacitor Discharge Ignition) technology was adopted for the H1.
This was not the only challenge to overcome, the massive horsepower developed by the new engine proved to be too much for the existing A1 or A7 frames. After much research, the frame design team decided to run twin frame rails from the steering head back to the seat rail and to reinforce them at three intermediate points. For the suspension, Kawasaki took their lead from the front fork pioneered in Italy by Ceriani. The team developed the first inner spring telescopic front fork to be incorporated into a large displacement Japanese motorbike. They also opted for a rear suspension with a three-position spring preload adjustable shock absorber.
The technical team overcame one problem after another, until finally they reached the point of test riding a prototype. They watched with immense satisfaction as their test model broke the 118mph barrier with ease. However, at this point another problem reared its head. Running a bike continuously at these speeds stripped the tread from the tyres! The technical team got together with Dunlop to develop the K77, a tyre that would stand up to continuous high speed running. Test runs were restarted and final development of the new bike proceeded on time.
In early 1968, Kawasaki conducted road tests in the USA. Kawasaki executive Darrel Krause (who was the US National Sales Manager at that time) enlisted the services of motorcycle racer Tony Nicosia to help in the development. The two of them did most of the secret road tests on the prototype in Arizona and Nevada. It is interesting to read Tonys notes, especially about the great handling!
Finally, approximately 14 months after the N100’s initial planning phase began, Kawasaki produced the first ever MACH III in September 1968. From the start of production into the early part of 1969, Kawasaki busied itself shipping samples of the new machine.
Tony Nicosia raced the new H1 at Willow Spring. It was the only bike Kawasaki had in the USA, and the weekend before it was due to be released to the Press, so they threatened to hang him if he damaged it!
At the time of its official debut the H1 was being touted as the fastest production motorcycle in the world.
To prove their point, Kawasaki shipped one of the first H1’s to Lyon’s Drag Strip, California in the crate. With media and local racers in attendance they uncrated the bike, assembled it, fired it up, and put Tony Nicosia on it with zero miles on the clock. On the first pass Tony ran a 13.10 at 99.66. After a few passes he then ran 12.96 at 100.70mph, the first ever sub 13-second quarter mile on a production motorcycle at 100 mph+. This was a master stroke as it not only silenced any doubters, but put the H1 in every motorcycle magazine in the world. Over the next few years Tony would amass world and national records all across the country on the H1.
Retailing at just $995 at a time when the average stateside selling price for a 750cc machine was around $1,400, the new machines became a best seller almost overnight.
It was the beginning of the triple legend.
Sources:-
Kawasaki Museum
Dragbike.com
Wikipedia
