N100 Plan

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).

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.

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