1972 Yamaha GL750 Prototype ??

[Frank B]

I just stumbled across this today, looks like it was a little ahead of its time. Too bad they didn't produce it...









     


   

   

Some info I copied..

Yamaha GL750 prototype, this is a fourcilinder two stroke. It was launched at the Tokyo motorshow in 1972. It had a two-stroke injection system which was also a prototype item for snowmobiles. It never reached production stage. Yamaha destroyed the prototype according to the German intenetsite zweitakte.de.

And some good info from Hooniverse 
https://hooniverse.com/two-wheel-tuesday-yamaha-gl750/

The two-stroke engine is rapidly fading from the motorcycling scene, but it played a much more significant role in the history of bikes than it ever did in cars, thanks to its higher output-per-pound and compact dimensions. And in the early 1970s, Kawasaki and Suzuki were upping the ante with huge new 750cc three-cylinder two-strokes.
While Yamaha's RD350 twin was heralded as perhaps the most powerful (per cubic centimeter), advanced and competitive two-stroke bike of the 1970s, Yamaha never stepped into the war of large-capacity two-stroke triples that was waging between Suzuki and Kawasaki. But they almost did.

In 1972, Yamaha used modified crankcases from their TZ700 roadracer to create a prototype four-cylinder, liquid-cooled 750 for the street. It outdid even its racing cousin by utilizing an experimental fuel injection system developed for Yamaha snowmobiles. Though it surely would have been detuned from the scary powerband of the TZ, it still would have been a rocketship unlike anything else on the street. The chassis was mostly standard production parts, and it was displayed to the public at motorcycle shows in Japan and Paris, so they were at least moderately serious about manufacturing the GL750. So why didn't they build it?

Yamaha commemorated the GL in this promo piece during their 50th anniversary.

Yamaha knew that the age of the heavyweight two-stroke multi was waining. Not only were restrictive noise and emissions regulations looming, but more and more riders were voting with their pocketbooks for the smoother, more refined performance of big four-strokes like the Kawasaki Z1 and Honda CB750. Yamaha had already already committed themselves to the development four-stroke heavyweight bikes when the GL750 was being considered. Their 650 vertical twin had already been in production for several years; it was well liked and was selling well.
While we may feel cheated out of the GL750, Yamaha made the right call. Kawasaki's H2 750 triple was discontinued in 1975, and Suzuki limped along with their GT triples until their four-stroke GS line-up appeared in 1977. The 500 and 750 four-stroke twins Yamaha went with rather than the GL750 grenaded themselves on the road regularly and bombed in the marketplace. But Yamaha did a better job with the shaft-drive, DOHC four-strokes that followed: the XS750 triple (later bored to 850 cc), and their XS11. Yamaha's RD350 twin got a 50cc overbore in 1976, and lasted until 1979. Its RZ350 replacement took a final bow in the U.S. in 1984-85.
Yamaha would eventually introduce a four-cylinder, liquid-cooled two-stroke in 1984, with the RZ500 Grand Prix replica. The XS650 twin was still in production at the time.