Remember seeing these? (No, neiher do I)

http://www.superbikeplanet.com/yamiow/

A lovely shot of the famed (infamed?) GL750 4cyl 2-stroke road bike.
Yamaha was killing them in the newly booming F750 class but the regs
demanded that the racers had to be based on road-bikes and Yamaha's
previously-dominant liquid-cooled 2-cyl TZ350 GP racer had been disqualified
because it differed too far from the air-cooled road-going R5.
The Yanks were racing at Daytona with TZ350 cylinders fitted onto the 4cyl
TZ500 GP racer's crank-cases (making a 700cc GP weapon) but it wasn't
eligible for the road-based F750 series until..... ta-da..... with much
fanfare the GL750 road-bike debuted at the Tokyo show.
Hey presto the TZ700 was suddenly eligible for F750 and it was so successful
that it basically killed-off the previously varied and interesting series.

The fact that the GL750 was never actually produced (and may never have even
turned a wheel under it's own power!) was quietly forgotten.