Coming Back with a 4-Stroke Powerplant

In the Suzuka 200-Kilometer Race, the sixth All-Japan race held in June 1981, the NR500 ridden by Kengo Kiyama put on a strong performance, taking advantage of the higher fuel efficiency its 4-stroke engine possessed. Maintaining a large lead over its rivals, his NR500 went on to take the checkered flag.

<< 1. Speeding Through the 1960s
<< 2. After a Decade, a Comeback to the Grand Prix
<< 3. Organizing the NR Block: Preparing for a Comeback
<< 4. Coming Back with a 4-Stroke Powerplant
<< 5. The Oval Piston: Heart of a New and Different Breed
<< 6. From Fantasy to Reality: Completion of the 0X Engine
<< 7. The Unconventional: Adopting a "Shrimp Shell" Frame
<< 8. The NR500s: A Humiliating Debut
<< 9. Refining the Engine-a Top Priority
<< 10. First Victory: The Suzuka 200-Kilometer Race
<< 11. The NS500, Honda's First 2-Stroke GP Machine
<< 12. Victory Again : After Fifteen Years
<< 13. Using Computer Analysis to Bring Honda Back, Stronger than Ever
<< 14. From the NR to Le Mans and Production Bikes

The first step toward Honda's World GP comeback was to determine the specifications for the machine they would create to achieve that goal.

Therefore, immediately after his transfer to HGA, Fukui began studying data from past World GP races. In 1977, the official regulations of the World GP specified a machine having four cylinders and six speeds. However, the majority of machines competing in the GP employed 2-stroke engines. It was to turn out that the World GP would be dominated by 2-stroke engines that year. Before 1977, the entries often included 4-stroke motorcycles, some of which even won their races. Accordingly, the data showed that there was no significant gap between the 2-stroke engine and its 4-stroke cousin.

The 2-stroke engine could no doubt generate power more easily than the 4-stroke. Moreover, its simplistic structure, which was free of camshafts and intake/exhaust valves, made the 2-stroke assembly as much as 20 kg lighter than a 4-stroke engine. The drawback was poor fuel economy, but that did not really matter, since GP racing essentially involved a sprint over a distance of approximately 100 kilometers.

However, the Honda team wanted to fight for the World GP title using machines carrying 4-stroke engines. They wanted to live up to the expectations of their company, a former champion that had taken 4-stroke technology to the summit of motorcycle competition. Often described as having "clockwork precision," the 4-stroke multicylinder engines, so brimming with technology, were a Honda trademark.

Therefore, it was not a matter of the Honda development team being so interested in running against the grain. Instead, their desire to win with a 4-stroke engine was simply a statement of what they knew to be true. The 4-stroke, multicylinder design was a winner.

So it was that Honda's return to the World GP using 4-stroke powerplants became a battle. It would be a contest of wills-a statement of honor-in which the company would put its most fundamental convictions to the test.
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