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 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.
Two Wheel Tuesday: Yamaha GL750
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as someone who raced a TZ700 (that later became a 750) way back in the day i would have to disagree with your "scary powerband" comment. coming off of a TD-1c, and then a TD-3, the four actually felt much more like a street motor. at least stock anyway. we uncrated ours, pulled the motor apart to check everything and replace the bearings with german FAG bearings, changed the tires and slapped on a set of S&W shocks and took it to sears point. i was a bit nervous for the first couple laps because of all the stories we had heard, but the 700 was far easier to ride than the air cooled twins!
it's kind of ironic that a shop had to show yamaha an AMA pro license just to be able to buy one, and now any kid can walk into a shop and buy a new 600 sportbike that will out perform a TZ700/750 in almost every way. with lights and turn signals and an electric starter… -
the GL would almost certainly have been faster than a GT750 (difficult not to be) and slower than an H2.
i paid for university selling DT's and RD350/400's and XS650's and later the TT/XT 500's. yamaha had a strange product line in the 70's. the company that dominated GP road racing produced pretty much crap street bikes with the exception of the RD's. the TX500 and XS750/850 were just dogs, and as much as i would love to have a mint 1975 XS 650 it was awfully long in the tooth and a tough sell by the late 70's.
the unofficial rumor about the license requirement was that yamaha was terrified that someone would put lights on one and put it on the street. -
Those are really interesting facts. Great Post!! Thank you very much!
Essay help -
there was rumour that Yamaha used the prototype Gl 750 to circumvent the F750 series rules so they could enter the TZ…and subsequently dominate the race series
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I rode a GT 380 back then and as said above the GT 750 and Mach III, RD350's /400s were all rocking the roads and making Bonnevilles Commandos and their counterparts look like they had been flogging a dead horse too long,. As I view the pictures of this GL750 which I did not know of till today. I notice some of the frame suspension and brakes components and recall how for street use the bikes were KILLING a lot of decent young blokes and still today MY habit of a sharp adrenalin shot kicks in occasionally as I head into a corner with a short braking distance and then relief as there is still room to brake ,already slowed enough to get around easily. In '79 that kind of incident was a crash with solid single discs and cross ply tires ,stiff compounds,stiff twin shocks and forks that made you wish a steering damper was available. IT is probably a better decision not to release a fuel injected 4 cyl. two stroke just yet at this time the GL was touted! ten years later with a catalytic converter and contoured radiator? I'd like to see that in a deltaboxIII with some massive brakes and monoshock now!
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I bought a new GT 750 in 1978 and No it was not as fast as the Kawa ,but I well remember the day I shaw one in the shop and they could not give them away.The gt 750 would last for more than 100,000 kms the Kawa would not The Honda 750 4 would , but the waterbottle was faster .One day I put it to the test 100f was the temp and I travelled @ 100M.P.H. The Yamaha would have had to be pretty special to out class the famous Waterbottle But if it was as good as the RD 350 Plus more cc it may have been
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Hi Neville, it’s nice to read all these comments from blokes who must be about my own age: 56. You claim that a Suzuki GT750 “Waterbottle” would outperform a seventies Honda CB750? Sorry son, by no means at all. As a teenager in the seventies I devoured all motorcycleroadtests I could lay my hands on here in Holland and I could almost dream all the quarter mile speeds and topspeeds of the 750 cc models in the seventies. The Gt750 was a nice calm touringbike, by no means a crazy racy widowmaker like Kawa’s 750 Mach IV H2. The H2 could outrun a bigger Kawa 900 Z1 on the quarter mile! The Suzuki GT750 had a topspeed of max some 111 mph, whilst the Honda CB750 could do some 119 mph. Kawa’s H2 could top 124 mph. And I agree too: Yamaha made pretty crappy motorbikes during the seventies, except for the XS650 and XS1100 types.
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Unfortunately for us, the Japanese engineers(?) were convinced buyers in the US wanted four strokes… I guess this is based on the hoopla the CB750 and Z1 gathered. With water cooling and fuel injection, the Yam would have been smooth, dependable, quiet, and a rocket. With a rider like Tony Nicosia on board, surely it would have run 11's out of the box, and saved Yam the embarrassment and costs of TX400's, 500's, 750's (hah). And XS650's? They sold a bunch in the early 70's to guys looking for a better Bonneville. Not sure they got it…Sorry, Yam screwed up
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@ Bob: I couldn’t agree more, kid! 🙂
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The bike had nothing to do with the TZ700 which came out two years later. Fuel injection was a ruse and non functional as was the entire bike. Yamaha was yanking Suzuki and Kawasaki's Tsubaki chains…..
http://www.classicyams.com/production-racers/prod… -
……yet, when it comes to looks, I still consider Yamaha’s GL750 as one of the most beautiful bikes that have been built during the good ol’ seventies. Such a pity they didn’t take in into production!!
But that goes for more bikes. I also regret it that Suzuki didn’t start up the production of their 1100 cc sixcilinder fourstroke Stratosphere model…
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