The Honda NR is a very rare street bike with a V4 engine, but that does not tell half of the story. Looking for a way to build a four-stroke GP500 engine that would beat the 500cc two-strokes of the late 70s, Honda had developed the NR500 GP bike, which used a four stroke V4 with oval pistons and eight valves per cylinder (32 valves in all), and two conrods per piston, hoping to find ways to make that engine breathe better and thus convert more air and fuel into power than two-stroke 500cc engines of that era.
|Not bad for a twenty year old machine! Notice the solo seat and lack of passenger foot pegs, the air scoop in the tail, probably to cool the high exhaust system, and the slightly portly appearance due to the laterally mounted oval pistons that widened the engine by around 10cm. Photo: Honda
The engine was frightfully complex and expensive to build, and did not provide enough extra power and driveability to beat the two-stroke machines. Honda gave up on the NR500 and switched to the two-stroke NS500 and its successor, the NSR500 that lead to multiple World GP500 championships in the hands of Freddie Spencer, Wayne Gardner and Mick Doohan.
The work on oval pistons led to the development of the NR, a road legal sportbike using a 750cc version of the NR500 engine that developed 125hp at 14,000 rpm – not bad for the early 90s. Only 300 or so were built, and sold for $50,000 a pop. Check out the pictures at http://en.wikipedia.org/wiki/Honda_NR
to see just how complex and wide the motor was.
Legend tells us that Honda had entered an NR in a 24-hour endurance race in France, with quick journalists aboard, as a proof-of-concept demonstration. Halfway through the race, the NR was in the lead, a few laps ahead of the Factory riders on RC30 bikes. The NR was stopped while mysterious gremlins were attended to, long enough for the RC30 teams to get back in the lead and win.
The Honda VFR750R, commonly referred to as the RC30, was another classic V4 design, using round pistons, a characteristic gear drive for the cams, and a one-sided swingarm, as did subsequent VFR street models up to 2009. Produced from 1987 to 1990, the RC30 was the basis for homologation of the model for Superbike racing at the world and national levels. RC30s won regularly in the hands of Miguel Duhamel in the AMA, and Fred Merkel, who won the World Superbike Championship in 1988 and 89 aboard the machine.
A clean RC30 sells for over $50,000 these days, while rare NR models are sold privately and prices are not disclosed.
And by the way, Swedish bike shops are that clean – all the time! I was there a few years ago and saw it with my own eyes
The video is at http://www.youtube.com/watch?v=YvmnSiVpoH8
|The RC30 looked compact and it was, making it extra agile on the track. The mechanical whine from the camshaft gear drive was music to the ears of true aficionados. Photo: Honda