Ten Most Unusual Production Motorcycles (Part 9)

1303

Honda NR

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The 1992 Honda NR (often mistakenly referred to as the NR750) was the most expensive production motorcycle at the time.

Please click here for Part 1 (Suzuki RE5), here for Part 2 (Honda CBX1000)here for Part 3 (Yamaha GTS1000)here for Part 4 (Suzuki Katana)here for Part 5 (Böhmerland)here for Part 6 (MTT Y2K and 420RR)here for Part 7 (Honda DN-01), and here for Part 8 (BRP Can-Am Spyder).

Honda had pulled out of motorcycle grand prix racing in 1967, only to re-enter in 1977. Two stroke machines had taken over the entire field in their absence, but Honda has always preferred to develop and race four-stroke bikes.

Honda knew that they’d be beaten by two-strokes and there was no allowance for bigger capacity four-strokes to compensate. The rules had stated 500cc engines with a maximum of four-cylinders, regardless if they’re two- or four-strokes.

Honda engineers worked around this by creating a high-revving V-4 engine, but with oval pistons. The oval pistons looked like two pistons being joined as one (think of a burger oblong).

 

With two conrods and eight valves per cylinder (yes, eight, for a total of 32 valves!) the engine gave the impression of a V-8. The engineers hoped that the bigger piston area would provide a higher volume air/fuel mixture, resulting in more power.

Honda unveiled the NR500 (NR stands for New Racing) in 1978 but the bike only made its debut in the 11th round (British GP) of the 1979 racing season. However, both bikes retired. The engine was overly complex. But Honda kept developing the bike and engine and came away with 130 bhp at over 20,000 RPM, matching the two-strokes.

Yet, the bike wasn’t competitive and Honda ultimately went on to develop the NS500 two-stroke tiple in 1982, ridden by Freddie Spencer, Marco Lucchinelli and Takazumi Katayama.

Still, Honda kept plugging away and came up with the NR750 endurance race bike. The technology was finally transferred to a road bike in 1992. Built in limited numbers, the NR (also known as the RC40) made 125 bhp at 14,000 RPM in the standard configuration. Priced at US$50,000, only 300 were built.

The NR featured many other innovative technology, including a single-sided swingarm, side-mounted radiators (a la NR500), and underseat exhausts, among other things. It’s also no secret that Massimo Tamburini was inspired by the Honda NR when he penned his iconic Ducati 916.

BONUS TRIVIA:

One of the engineers who worked on the oval piston project revealed that while trying to reduce the number of valves to the more conventional 4 valves per cylinder to improve combustion and power in the low- and middle-RPM range. That development led to one of Honda’s most famous technology and was first featured on the CB400 Super Four.

The VTEC.

So, the VTEC wouldn’t have been possible if not for the oval piston research and development.

Please click here for Part 1 (Suzuki RE5), here for Part 2 (Honda CBX1000)here for Part 3 (Yamaha GTS1000)here for Part 4 (Suzuki Katana)here for Part 5 (Böhmerland)here for Part 6 (MTT Y2K and 420RR)here for Part 7 (Honda DN-01), and here for Part 8 (BRP Can-Am Spyder).