Republished from March 2016

JUST AS Moto Guzzi’s 275kmh 500cc V8 ‘Otto’ astounded everyone in 1955, Honda’s technologically courageous  NR500 left everyone gobsmacked in 1979. In fact, 37 years later, most people’s gobs remain as smacked as ever. Some folks reckon the NR was a stroke of genius. Others reckon it was sheer lunacy. A few of us, of course, are clever enough to know there’s no difference between the two.

If you’ve ever read anything about the NR500, you’ll know that it wasn’t a V8 at all, but a V4. Or that was Honda’s story anyway. But I say it was a V8. Stay with me … and wait till you see the pic.

CAPTION: A rare view. Not many riders saw the rear end of an NR on the race track.

A little history.

In 1954, the very same year that Moto Guzzi created the Otto, Honda became the first Japanese motorcycle manufacturer to take part in a formally organised international racing event; competing in the 125 class at a commemoration event in Brazil that marked the 400th (!) anniversary of the city of Sao Paulo. Honda’s R125 had a top speed of 110kmh. Not bad for 125cc engine more than 60 years ago, eh? But the winning Mondial 125 from Italy was good for a breathtaking 160kmh. Needless to say,  Honda got spanked. And guess what? They didn’t like it.

We’ll be back, they vowed.

Fast forward just seven years. At the Isle of Man TT races in 1961, Honda finished first, second, third, fourth and fifth in the 125cc and 250cc classes. Cop that, they said.

Honda stuck around on the GP circuit for a few years then withdrew in 1967, figuring they’d proved their point.

CAPTION: Chassis design on the NR500 was almost as ground-breaking as the engine. Note side-mounted radiators (way ahead of their time) and weird windscreen shape.

By the late 1970s Honda had been out of the racing game for more than a decade, during which time everyone else had moved on from four stroke motors to two strokes. The two strokes were lighter, faster … better. But Honda believed four stroke engines were part of the corporate DNA, and if they were going to have a fresh crack at the GP circuit, it was going to be with a four stroke engine.

Given their druthers, Honda’s engineers would have liked to build a 500cc V8. Just as Guzzi had deduced in the 1950s, the V8 configuration would enable the engineers to cram 32 valves into the heads, thereby allowing plenty of fuel and air in and out, and eight spark plugs to do a decent job of burning it all. Trouble was, V8 engines were specifically precluded by the rules. Sorry folks. No more than four. (Maybe they were frightened Guzzi would roll the Otto out again?)

So how do you get 32 valves and eight spark plugs into a four cylinder engine? Like this:

CAPTION: Eight con rods. Eight spark plugs. Thirty two valves. And you’re telling me it’s not a V8? Sure … so that’s why they’re called con rods.


Look closely at that picture. Thirty two valves. Eight plugs. Eight con rods. See why I called it a V8? Because, frankly, it is. The oval pistons (well, rectangular with rounded corners, really) are just two round pistons siamese-twinned and built as one.

So how did it go? Well, like the Guzzi Otto, it was an engineering marvel and something of a masterpiece. But, like the Guzzi Otto,  when it wasn’t getting towed back to the pits it was mostly getting spanked. And guess what? Honda didn’t like it.

By 1982 Honda’s GP bike was a two stroke — the three-cylinder NS500. Twenty-one-year-old American Fast Freddie Spencer delivered Honda its first world title of the modern era aboard the NS500 in 1983.

The NSR500 with which Aussie Mick Doohan delivered Honda world titles in 1994, ’95, ’96, ’97 and ’98 was a traditional V4 two stroke. With round pistons …

Incidentally, the oval pistons did make their way onto an over-the-counter production bike. Honda released the 750cc NR in 1992. It was hellishingly expensive at the time ($50,000 give or take) and they’re even more expensive if you can find one today. Don’t expect to find a set of rings in stock at your local Honda dealer …



CAPTION: The 750cc NR. I spotted one for sale in the UK recently for a tad over $145,000 AUD. Spare parts might be a problem …

Also read:

Guzzi’s V8 racer

The Britten V1000 — DIY perfection

Peter Terlick