|The NS500, Honda's First 2-Stroke GP Machine
The NR500s were indeed struggling to achieve any results on the World GP tour, and even the members of the NR Block had begun to lose their patience. After all, they had not been asked to demonstrate winning potential but to "win the race." The NR Block might have been just one of many groups within the Honda organization, but to the fans watching the race they represented none other than Honda itself. They just could not go on without a win, since a losing streak on the circuit would affect sales of Honda motorcycles and cars. Moreover, no action would be timely once the image of a powerless company had taken root among consumers. Potential was no longer enough. The development staff had no choice but to defend itself by winning.
Finally, a proposal to develop a machine carrying a 2-stroke engine was brought to the table for discussion. The proposed NS500 would have better performance than the NR500, at least theoretically, and the data-though it was basically a prediction-was not something with which anyone could argue. For its part the development team would no longer insist on the 4-stroke engine.
Thus, it was that the in the middle of the 1981 World GP season the NR Block began developing NS500 machines carrying Honda's first 2-stroke engine design. Assigned to the post of project leadership was Shin'ichi Miyakoshi (then the chief research engineer at HGA's NG Block), a veteran engineer who had designed engines for GP machines in the 1960s, during Honda's domination of the series. When the NR500 development started, Miyakoshi was designing engines for motocross bikes at HGA. After his motocross group had merged with the NR Block, he began working on motocross machines within the context of the NR Block.
Miyakoshi's original concept at the beginning of development was to make the NS500 a "compact, lightweight machine." Thus, once he had received the assignment to design a 2-stroke GP machine, Miyakoshi visited the Netherlands in June 1981, so that he could watch the Dutch TT Race held in Assen. There, he confirmed that there was basically very little difference in the lap times of 500 cc machines and 350 cc machines. The fastest bike in the 350 cc class could have started the 500 cc race from a position in the second row.
Accordingly, Miyakoshi envisioned a machine that, though it was a 500 cc unit, had the compact size of a 350 and a smaller frontal projection. Moreover, it would be equipped with an engine designed for optimal control rather than higher top speed. It would be a machine built to achieve total balance, and the idea had Oguma's full agreement.
Miyakoshi quickly aligned the vectors of staff members, each of whom was experienced at weight reduction through involvement with the NR500. From that point on, development would proceed rapidly. For reduced size, the engine would feature a unique 2-stroke, 3-cylinder V layout. With regard to the intake valve, the team chose a lead valve used for motocrossers rather than the usual rotary type used for road bikes. The lead valve was considered advantageous since it demonstrated no loss in power and pushed-started more easily. After all, a head start could give the machine a lead of at least three seconds, and those three seconds could well determine who crossed the finish line first.
The effort to reduce size went well beyond the confines of the engine. Having succeeded in getting a partner supplier to shorten the sparkplug, Miyakoshi then reduced the wheelbase by 25 mm. This made it possible to handle the 500-cc machine as easily as one would a 350. Furthermore, the NS500 incorporated the suspension technology Honda had accrued through the development of motocross bikes, greatly enhancing the combativeness and maneuverability of this new roadracer.
"A racing machine doesn't just consist of an engine and frame, " Miyakoshi recalled, " it's supported by the peripheral technologies of partner manufacturers. In developing our new machine, we learned a great deal from the advice given by the engineers at Mugen, an engineering company specializing in racing technologies. If the source of ideas had been limited to our staff members, omissions might have prevented us from achieving the right balance."
Although it was just behind Honda's 4-cylinder machines in terms of brute power, the NS500 had a maximum output of 120 ps at 11,000 r.p.m. and a maximum torque of 8 kg-m at 10,500 r.p.m. Additionally, the superb total balance of the machine fully compensated for any gap in power. Ultimately, the completed NS500 represented a cross between a roadracer and a motocross bike.
The NS500 team assembled to fight the 1982 season included Spencer, Katayama, and Marco Lukineri, who was the 1981 champion. Although the team regarded as their key force the NS500 machines powered by 2-stroke engines, they continued to race an NR500 under the ridership of Ron Haslam. Moreover, Honda refined its definition of responsibilities for the team manager, appointing Oguma to the post.
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