The N100 Plan was the corporate code name for the top secret concept, engineering, and development of an entirely new motorcycle engine by Kawasaki Motorcycle Corporation, a division of Kawasaki Heavy Industries in 1966.
The goal of Kawasaki engineering in the N100 Plan was to create a large bore, fast motorcycle engine for entry into the American market, the largest market for motorcycles. Honda had already introduced its successful Honda CB450 in 1965 and Kawasaki desired to enter that large bore niche.
The N100 Plan called for an air-cooled standard motorcycle with an engine capacity of 500 cubic centimeters. The power output was set at no less than 60ps (equivalent to a per liter horsepower of 120ps). The performance minimum was to make a 13-second standing start 1/4 mile run (0–400 meters).
Three cylinder development
The Kawasaki engineers approached the N100 Plan in two ways. (1) Use an existing, tried and true Kawasaki A7 350 "Avenger", a 350 cc two-stroke, parallel twin-cylinder, rotary-disc engine, bored out to 500 cc or (2) develop an entirely new engineering layout, building a parallel 3-cylinder two-stroke or create a new and groundbreaking "L-triple" design air-cooled two-stroke engine.
The development team decided to utilize both twin-cylinder and triple-cylinder engines together as test engines. The largest concern was development of the 3-cylinder design and whether it would be a parallel in-line or new "L-triple". The concern over the 3-cylinder design was cooling cylinders #2 or middle cylinder in either application. Osaka University's laboratory belonging to the Faculty of Engineering performed a number of tests on cooling of the engine as a whole, optimum length of cooling fins, and optimum cylinder pitch. It was determined that a parallel in-line configuration would not impair cooling.
While testing the 3-cylinder, Kawasaki also went forward with the development and testing of its current two-stroke twin-cylinder rotary disc valve engine. The preliminary test results pointed to a very promising outcome. One possible advancement in the twin over the triple was keeping the rotary disc valve fuel/air intake which produced more horsepower than the conventional piston port or reed valve means which has been the case in other Kawasakis.
The initial part of the 2nd test of the N100, as recorded by Darrell Krause, was between Los Angeles and Las Vegas in late 1968 with the test rider Tony Nicosia. A new engine was installed at Las Vegas and the bike was run to Yuma, Arizona under normal road conditions with a return trip to Los Angeles. Krause reported improvements at low speed, better electrical performance, and improved oil consumption @ 350 to 400 miles per quart. Problems were listed as bad piston and clutch noise.
Testing in the U.S. was administered by Darrel Krause, one of the first few US employees hired under Yoji (George) Hamawaki. Krause majored in mechanical engineering from the South Dakota School of Mines & Technology. He had moved up through the ranks of Kawasaki from a Kawasaki/Suzuki dealer to become one of the first corporate employees of American Kawasaki known under the acronym then as AKMC. Krause's positions were Service Manager, Racing Manager, New Products Manager, General Manager of the Kawasaki Engine Division, and General Manager of Kawasaki Accessories Division located in Santa Monica, California. One of the his first duties in 1966 was to commission a U.S. marketing plan for Kawasaki.
In 1969, Kawasaki debuted the Kawasaki H1 Mach III with interest and it was eventually labeled in various ways as the "world's quickest accelerating production bike". The success of the Mach III directly lead to the development of the Kawasaki Mach II S2 350 in 1971, the Kawasaki S1 Mach I and Kawasaki H2 Mach IV 750 in 1972.
- The term N100 was written about most authoritatively by Dragbike Magazine's  article on the Kawasaki H1.
- The early 1970s Kawasaki single and twin-cylinder motorcycles with rotary-disc valves produced on the whole more horsepower than their competition by Yamaha and Suzuki. Chuck C., Kawasaki mechanic, Juno Cycle Center; Juno, Florida, 1971-1973. Email correspondence, July 2010.
- Margie Siegal (January–February 2011). "1970 Kawasaki H1 Mach III". Motorcycle Classics. Retrieved 2011-12-15.
- Dragbike news features, A Look Back In History...The H1 Triple - 1969-1975 (bulk of article's content).
- Dragbike, H1 History
- Report (.jpg file) dated December 2, 1966. N100 Second Test, by D. Krause.
- Kawasaki Accessory Division News, Accessory News, 1974
- Cover of marketing report by Clinton E. Frank to D. Krause.
- Darrel Krause biography, Product Development Consultant Jeff Krause website.