The Honda NR(New Racing) was a V-four motorcycle engine series started by Honda in 1979 with the 500cc NR500 Grand Prix racer that used oval pistons. This was followed during the 1980s by a 750cc endurance racer version known as the NR750. The oval piston concept allowed for eight valves per cylinder which generated more power due to the increased air/fuel mixture throughput and compression. In 1992 Honda produced around 300 street versions of a 750cc model, the NR (often mistakenly referred to as the NR750), with a 90-degree V angle. Whereas the NR500 had used an oval piston with straight sides, the road going NR750 used an elliptical piston with curved long sides. The bike became the most expensive production bike at the time when it was selling for $50,000 and with the rarity, nowadays they rarely change hands.
NR sttod for "Nearly Racing" when it was forever breaking down in Grand Prix races.
Not really Honda's best concept.
Martyn
__________________
You're never too old to learn something stupid.
TTR250 but now a mobility scooter Budleigh Salterton
Ah the days of innovation, anyone remember the Yamaha TZ 350 and 750 race bikes, they had a novel idea, tapering barrels, that got smaller towards the top, great for compression in the short term, as for lasting more than two races not a chance.
__________________
Riding with enthusiasm upon the ragged precipice of disaster
Talking of innovation, one of the most distinctive exhaust notes I can remember was from a Mazda rotary engined car which was racing in the saloons at Brands Hatch in 1976 (Noel Edmonds was racing in this class I recall) - I think this was the car:
The only Grand Prix I have been to and James Hunt won it