Fifty years ago, give or take a week or two, the most unlikely racing motorcycle of all time won what was then the most important bike race in the world. Okay, to be completely fair, our recent fixation with racing “baggers” is probably weirder and, in 1976, long before WSB racing became a thing, the “Superbike Production” race round at Daytona played second fiddle to the industry-dominating “200.” Nonetheless, Steve McLaughlin’s triumph aboard a BMW R90S was so unexpected, it was the motorcycling story of the year. That the BMW would also win that entire series — again the first “superbike” class anywhere in the world — this time with Reg Pridmore in the saddle, literally dominated the year’s motorcycle industry. If you don’t believe me, drop by the house sometime and I can show you all that year’s issues of Cycle, Cycle World and Motorcyclist. BMW’s R90S rocked the world.

And while the race being won by an air-cooled twin originally designed for portable industrial use — or that said racer, in stock trim at least, barely made 60 horsepower — was the headline news, there was much behind the scenes action that makes this story even more of a classic. 

For instance, race-winner — and 1976 series runner-up — McLaughlin may now be famous for creating the World Superbike Racing series in 1988, but at Daytona in 1976, he wasn’t initially supposed to even be riding the BMW. His assignment was so last-minute, he rode the back-up bike — the “spare-parts bike” in the race, according to Udo Gietl, the famed boss of Butler & Smith Racing. In fact, according to Gietl, McLaughlin’s bike was such a last-minute addition to the race that it was still running a points ignition system — liberated from a Honda 305, no less — and was, in fact, the test mule. 

And neither Pridmore nor McLaughlin might have been BMW’s premier rider on that day. That honour, at least temporarily, rested with Gary Fisher, who had previously raced for Butler & Smith in the F750 class. Fisher, the son of famed racer Ed Fisher, took pole that year and led the race until he suffered a mechanical failure. In other words, that famed Daytona race might well have been a complete 1-2-3 sweep — the official results were McLaughlin 1st by less than a foot over Pridmore — if Fisher’s gearbox hadn’t packed it in.

Despite these behind-the-scenes shenanigans, it remains the incongruity of BMW beating the might of Honda and Kawasaki inline fours — not to mention much more race-bred twins from Ducati and Moto Guzzi — with, what was, when it was originally designed in 1920, meant for generators and water pumps. 

One of the main obstacles was that the flat twin was enormously wide and had limited cornering clearance, a problem that Gietl remedied by shortening cylinders, installing 10 mm shorter titanium connecting rods, and then bevelling the hell out of the valve covers. 

Then there was the problem of the BMW’s impossibly long pushrods. Most performance-oriented overhead-valve engines put their camshafts as close to the cylinder head as possible; short pushrods are stiff pushrods and therefore are less likely to bend when the revs get nasty. BMW didn’t have that choice, since its centrally located cam was right beneath the crankshaft, quite literally as far away from its rocker arms as technically possible. 

Gietl’s solution was high-strength steel pushrods shaped like fat cigars. He added super-long durations camshafts with ramps gentle enough to limit valvetrain acceleration and topped the entire mess off with super stiff valve springs — as much as 280 pounds at full lift if technical writing legend, Kevin Cameron, is to be believed — to keep the valves pinned to the cam lobes. The result was said to be close to 100 horsepower with useable revs as much as 3,000 rpm higher than the stock engine.

Gietl was even more, let’s call it, adventurous with the BMW’s chassis. Although all manner of modifications were permitted to the engine, technically, the frame was supposed to be the “production” part of the series name. The R90S was anything but stock. For instance, to keep bendy frame rails in line, Gietl added braces that ran from the head stock to the swingarm pivot point. 

Now, one can make the argument — and, seemingly, Gietl did — that adding a brace is not the same as modifying a frame. But if you want to see how much the “spirit” of the rules was violated, take a really close look at the left side of the bike, where you’ll see that the “brace” actually ran right through the Dell’Orto carburetor’s velocity stack. And as if that wasn’t cheating enough, he replaced the stock R90S’ twin rear shock with a single car-based Koni monoshock. No surprise, given BMW’s complete dominance in 1976, that the rules were more rigidly enforced the next year.

Perhaps the most enduring part of this story, however, is that racing is expensive. BMW reportedly spent USD$250,000 — a million and a half greenbacks in today’s money — winning the inaugural American Superbike championship. And while that might seem like a pittance today, it was an incredible sum in 1976 for a racing program that, at the time, was just a support series. BMW pulled its funding and, even if Gietl did field some bikes as late as 1978, his support was limited to his access to parts returned under warranty. 

Some stories — like BMW beating Kawasaki’s famed 900 with a pushrod twin — are unique. Others are as old as racing itself.