2. NR750

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The NR series features the only engines in existence constructed with oval pistons. Originally designed in the late ’70s as a four-stroke competitor to the 500cc two-stroke engines dominating Grand Prix motorcycle racing, the oval-piston V-Four engine is decidedly unique. With eight valves per cylinder and eight connecting rods, it’s nearly a V-8, but it was never able to match the lightweight two-strokers in GP competition and was replaced by the two-stroke NS500 in the early ’80s.

The NR750 was the culmination of this racing experience and technology presented in limited (300 examples) street-legal form to those who could afford a $60,000 motorcycle in 1992. Comparatively, Ducati’s Desmosedici sold for $72,000 in 2008. Like Chief Editor, Kevin Duke, says in his Exploring Lightweight Materials article, “There is literally nothing else like it and probably never will be again.”