In 1971, I was no more than a pup, but that was probably about the time I started reading all the motorcycle magazines at the drugstore, of which there were a bunch. Twenty years later, when writing motorcycle magazines became my business, and I spent a large amount of time rooting through back issues in the library (how quaint) and old press kits – BG (before Google) – I’d still never seen this motorcycle until somebody threw it up on Facebook a few days ago, on the Classic Japanese page. (I’m told it was on the cover of Cycle Guide back in the day, don’t know how I missed it?)

 

What it is, is Yamaha’s prototype for a streetbike it was thinking about building to compete with Kawasaki and Suzuki’s open-class two-strokes – the now-legendary Kawasaki H2 moreso than the more mundane Suzuki GT750. Here’s the scoop from the Yamaha Community of France:

The GL750 is presented to the public for the first time at the Tokyo Salon 1971. But it is at the Paris Salon of the following year, in autumn, that it creates the sensation and that the French can admire the sculptural Japanese realization on the Sonauto Yamaha stand. Thanks to the pugnacity of Jean-Claude Olivier, the two-stroke liquid-cooled four-cylinder engine with injection fuel, is featured on his podium. This will be the only time that the GL750 will leave the Japanese soil. Never manufactured in series, because of the forecasts on the sound standards and of emission of CO2, it remains a “belle de salon” equipped with many dummy pieces. We will recognize however the drawing of some of them on other models; the dashboard of the TX750and the low cases of YZ648 (or TZ700prototype) are examples. Its type of four-cylinder engine in line, with liquid cooling (without the injection), will however obtain in the competitions 500 and 750 of magnificent results among others with the TZ700 and TZ750 , titles in support.

The translation is slightly wonky, but you get the gist.

Three years before the TZ700 and 750 that basically revolutionized roadracing, Yamaha had the building block already in place in this GL 750 (before Honda’s first GL1000) streetbike.

Say, those aren’t carburetors.

You never know what’s inside a “prototype,” and I haven’t found anything from anyone who claims to have heard this one run. One source said Yamaha was already building fuel-injected snowmobiles at the time, but all the vintage Yamaha sleds you can still get parts for here use carburetors, and the first fuel-injected streetbike wasn’t going to come along for another decade in the form of the 1980 Kawasaki Z1 Classic.

So, in spite of the fact that the TZ engine appears to be a very real thing, maybe a show bike was all the GL 750 was ever intended to be: 1971 was the year the U.S. Environmental Protection Agency began doing away with the American muscle car through strict new automotive regulations, and the same time frame saw the smashing success of the `69 Honda CB750 and Kawasaki Z1 four-strokes.

Looking back from 50 years, the H2 Mach IV Kawasaki triple is now an exotic collectible, but in 1972 it was kind of a crude old thing compared to the sophisticated and smooth new Z1, and after 1975, the H2 was history. No doubt the liquid-cooled Yamaha would’ve been smoother and more powerful than the H2, but the writing was on the wall. In fact, after 15 years of nothing but two-stroke motorcycles, Yamaha had built its first four-stroke in 1970, the XS-1 650 twin. Followed by the XS750 triple in 1976, then the full-zoot XS1100 four-cylinder in 1978.

Still, Yamaha’s first production RD250 two-stroke appeared the same year the GL 750 made its appearance at the Paris show, and that RD, which grew into RD350, RD400 and then RZ350, was wildly successful and still widely popular. RD/RZ500, sadly, was banned in America, but not until 15 years after the GL.

A good-running private TZ750 was supposedly good for 135 horsepower or so; a stout street-going GL 750 might’ve made an easy 90, which would’ve made it performance king for most of the `70s if the tires and chassis components had been able to keep up. In those days, the aftermarket would’ve had a field day with the GL.

But it never happened, which is probably a good thing for thousands of mothers and untold trillions of oxygen molecules. What might’ve been…