Starting in the mid-1960s, Honda was very reluctant to build two stroke motorcycles. It didn't fit with their philosophy of aligning their racing solutions to their production offerings, as we covered in our article about the RC166. When they finally committed to the two stroke again with the NS500, they got competitive very, very quickly.
In 1984, Honda designed it's second attempt at a two stroke motorcycle for the 500 cc Grand Prix World Championship with the NSR500. In doing so, they only designed what would prove to be one of the most dominant motorcycles in racing history.
With the NSR, Honda migrated from the three cylinder engine in the NS to a V4 design. Right away, the new power plant was competitive. It's a reasonable question to ask why did Honda bother to create the V4 NSR500 when Spencer had just won Honda’s first 500cc crown in 1983 on the NS500 triple, beating Kenny Roberts‘ fiery Yamaha OW70 V4 in the process? The NS wasn’t nearly as powerful as King Kenny’s unwieldy V4 but it was a much more rideable package. But Spencer told Honda they needed more horsepower, so it was going to have to be a four cylinder. The new engine utilized a single crankshaft. This made it a much lighter solution than its competitors, most of which were still utilizing dual crankshafts.
Spencer debuted the bike in March 1984 at Kayalami, South Africa. Despite the promising new bike, things didn’t start well. The bike’s carbon-fiber rear wheel collapsed, injuring Spencer and putting him out of the race. The 1984 NSR’s problem wasn’t lack of speed either, the bike managed 140 horespower at 11,500 rpm. It's Achilles Heel was the innovative ‘upside-down’ chassis design. The fuel tank was mounted below the engine with expansion chambers sweeping back above the motor, to create a low center of gravity. However, the NSR’s center of gravity was actually too low, so the bike wouldn’t transfer weight into and out of corners to aid front and rear traction. The low slung tank also sloshed fuel forward under braking, causing major understeer.
But in typical Honda fashion, the following year in 1985, they developed a newly evolved chassis as well as a mildly improved engine. Freddy Spencer provided Honda their second 500 cc Grand Prix championship.
By 1987, the engine underwent significant modifications. The cylinder bank angle increased to 112°. This made it easier to make room for the four 36 mm carburetors, and allowed them access to cooler air. The new engine layout also allowed a better solution for the expansion chambers. Honda yet again won another title in the hands of Australian rider Wayne Gardner.
For 1988, despite their success the previous year, they started with an entirely new bike. The chassis transformed into a twin spar aluminum type, and significant engine improvements pushed output to 165 hp at 12,000 RPM. The new bike was capable of more than 190 mph. It quite simply accelerated faster and had a higher top speed than any other bike on the track. Not surprisingly, Honda won yet another championship in 1989.
By 1990, the NSR development effort was out right dominant. The 499 cc V4 engine was producing in excess of 200 hp, and the chassis was one of the best in the field. The Australian Mick Doohan seemed a perfect fit for the NSR500. Despite not winning the championship in 1992 due to a broken leg mid season, he won 5 of the first 7 races before the incident.
That was only the beginning for the Doohan / NSR pairing. Starting in 1994, Doohan and the NSR500 won five consecutive 500 cc world championships. In 1997 specifically, he broke a single season record for overall victories - winning 12 of the 15 races. No combination of one rider and motorcycle has ever been more dominant. Doohan won 54 total 500 cc Grand Prix races aboard the NSR.
In all its various permutations, the NSR500 won 10 world championships from 1985 through 2001. The NSR500 had more than 100 Grand Prix wins to its credit. It completely dominated 2-stroke racing before the introduction of the 1 liter four stroke formula took over.