SUZUKI GT750
Fifty years ago, Suzuki launched the first liquid-cooled Japanese production bike – the GT750. The two-stroke triple still radiates charm, but what’s it like to ride half a century later?
We throw a leg over the 50 -yearold liquid-cooled stroker triple
The early 1970s spawned a new generation of bikes – the so-called ‘superbikes.’ And, while the original superbike – Honda’s CB750 – is technically a child of the ’60s, it was early on in the following decade that this new genre really came of age. The holy trinity of the big-bore machines that changed the face of motorcycling was made up of the game-changing CB750, Kawasaki’s awesome Z1 and Suzuki’s big, brash GT750. Almost half a century later, all three bikes have well and truly nailed their classic credentials – but, arguably, it’s the Suzuki that really dared to be different.
The CB750’S main selling point was its single overhead cam, across-the-frame, four-cylinder engine – a unit that drew on Honda’s years of experience with chain-driven ohc engines and their superlative racing fours. Kawasaki (who had their own four-cylinder prototype in preparation) upped the ante in 1972 – after being beaten to the draw by Honda in 1969 – with their bigger, faster and more sophisticated Z1, with a double overhead cam top end. But Suzuki stuck to what they knew best to produce their biggest two-stroke to date - a three-cylinder, water-cooled 738cc tour de force. Though the GT750 looked like nothing Suzuki had produced before, it actually drew on an existing and proven model, the T500 twin. Underneath the water cooling and cleanly-finished new castings, the GT750 engine is essentially a T500 twin with an extra cylinder grafted on. The T500 had proved both supremely reliable and an impressive performer, so it made sense for Suzuki to base the new triple on such a solid foundation, therefore the big GT shares bore and stroke dimensions with the 492cc twin. Although the T500 had proved a little underpowered for the cube-hungry American market, the GT750 pumped out a healthy 67bhp, according to Suzuki’s figures.
They opted not to go for all-out power with the GT750, though. Despite the fact that their Gt750-derived TR750
‘SUZUKI STUCK TO WHAT THEY KNEW BEST TO MAKE THEIR BIGGEST TWO-STROKE TO DATE, A 738cc TOUR DE FORCE’
race bikes proved blisteringly fast, they preferred to target the touring market with an impressive spread of smooth, useable torque from relatively low revs. Maximum torque – a claimed 55.7ft lb – arrived at a relatively lowly 5500rpm, while top speed hovered around the 110mph mark.
There are no short cuts in the engineering. Horizontallysplit crankcases house a massively constructed, pressed-up, 120° crankshaft with four main bearings. The helical gear primary drive is taken off the crank between cylinders two (middle) and three (right-hand side), allowing the crankcase/ gearbox to be narrower behind the cylinders. The three sets of points and condensers for the ignition mount on the left-hand end of the crankshaft, as does the sprag clutch for the starter motor, while the alternator mounts on the righthand end. Roller big-end and small-end bearings are employed and the two-ring pistons are very similar to those of the T500, while the one-piece cylinder head features fairly shallow combustion chambers.
So far, so conventional – but it’s the water-cooling that makes the GT750 a standout design for 1971. As on
most cars, the system is pressurised and incorporates a header tank to protect against boiling over. A vane-type water pump in the bottom of the crankcases shares its gear drive with the tachometer and pushes the nine pints (approximately five litres) of coolant round the water jacket surrounding the cylinders. From there, it flows up into the head before passing through a thermostat, from where it is either routed directly back to the pump or, once the coolant temperature reaches 82°C when the thermostat starts to open, into the radiator before returning to the pump. A fan, mounted behind the radiator, cuts in at 105°C. Extensive testing of the cooling system in west coast America’s summer failed to trouble it.
The rest of the bike broadly follows established Suzuki practice of the day. The CCI automatic oiling system is the same as used on the T500 and provides positive lubrication of the main and big-end bearings, too. The engine is rubber mounted to isolate the rider from vibration, the frame is a sturdy duplex cradle affair and the three-into-four exhaust system incorporates a balance pipe between each of the three downpipes, which not only contributes to silencing but also increases torque at low revs significantly.
Cycle parts are nothing ground-breaking, either – they’re simply well engineered, nicely finished and well put together. Only the front brakes – a double-sided twin-leading-shoe unit – are a little out of step with 1971 superbike convention. They work (just about) well enough, but the future was with discs and twin discs appeared on the second incarnation of the GT750, the 1973 K model.
The styling of the GT750J, though, is right on the money. The ’60s were over – this was the bold, brash ’70s, and the big GT embraced the new decade enthusiastically. Take the colour schemes for a start: Candy Lavender, Candy Yellow Ochre, Candy Jackal Blue. Nothing says the ’70s as loud as paintwork like that. The engine and exhaust might have been whisper quiet, but the GT750’S paintwork and simple yet bold graphics were anything but. And, rather than try to hide the broad expanse of radiator hanging in front of the smooth-looking water-cooled engine, Suzuki’s stylists made it into a statement. Much like the four silencers of Honda’s CB750, the radiator with its coloured accents on each side and chrome protector bars became a badge of honour. Here was the first water-cooled Japanese production bike. Modern, sophisticated and technologically advanced. Admire. And many people did. When the GT finally arrived in the UK for the 1972 sales season (Japan and the USA got the first production bikes in ’71), it received a warm welcome – despite the fact that the UK only got around 500 first-year J models. Motorcycle Mechanics magazine described it as: ‘... one of the best bikes we have tested. It is extremely fast and comfortable, has impeccable road manners and really
is terrific.’ Over the top? Well, I’m about to find out... To make my own mind up, I’ve persuaded Anthony Godin, the affable proprietor of Godin Sporting Cars and Motorcycles in Mereworth, Kent (anthonygodin.co.uk) to let me out for a morning on a very tidy looking J model from his showroom. It’s a launch-year machine, but was first registered in October 1972, making it one of the relatively few bikes officially imported to the UK that year. Totally restored in 2015 by the previous owner, the engine was rebuilt by noted GT specialist Chris Applebee, with the crank rebuilt and balanced, new pistons, rods, bearings, seals – the works, in fact. It should be a good ’un.
By the looks of it anyway, it is. Anthony tells me the respray the bike underwent at the time of restoration isn’t quite the right shade of Candy Lavender, but I wouldn’t have noticed and it looks a treat to me. What I do notice is how well set-up the bike feels when I throw a leg over it outside Anthony’s showroom. With a bit of choke – the
‘THE CIVILISED ENGINE PULLS DECENTLY FROM AROUND 2500rpm AND IS ALMOST UNNATURALLY SMOOTH’
lever is conveniently mounted on the left-hand handlebar – the briefest stab of the starter button has the GT’S engine burbling away beneath me. That extravagant, three-intofour system certainly makes a good job of silencing the exhaust note, and the water jacket on the cylinders muffles engine noise pretty effectively, too. After a few moments to get some heat into the engine, I can pull off without fuss – and a mile or so later I can shut off the choke completely and start to explore what the bike has to offer.
The engine feels so civilised. It ticks over perfectly, pulls decently from around 2500rpm, albeit accompanied by a little induction roar until the revs build a little, and is almost unnaturally smooth. That’s perhaps partly because it’s a two-stroke triple with a 120° crank. With the engine firing twice as often as a four-stroke, the frequency of the power pulses is the same as that of a six-cylinder four-stroke.
But the big smoothy is decently fast, too. Cranking up the revs a little gives serious urge in the midrange – perfect for overtaking moves without having to drop down the admirably positive gearbox. So, it may not be as fast as a good Honda CB750 and certainly not in Kawasaki Z1 territory, but these days, frankly, who cares? Here’s a
classic bike that will cruise all day at 80mph without fuss or reliability issues. And if a 107mph top end isn’t enough for you, maybe 50-year-old classic bikes aren’t really for you. Those tls front brakes are pretty good, too – they’ve obviously been set up just-so on this machine.
Sure, the GT750 is heavy (despite Suzuki’s brochure claims of a 472lb (214kg) dry weight, I’d put it at over 500lb (226kg) plus fuel and oil, but it feels wonderfully poised at low speeds. Feet-up, full-lock U-turns are easy thanks to the balanced feel of the bike, and its smooth power delivery and progressive clutch action. As for the GT’S handling, oft-derided in the day, it isn’t anything like as bad as detractors would have you believe once it’s shod with decent, modern tyres like the Conti Go rubber fitted to this one.
By the end of a (sometimes damp) morning on the GT750, I’m seduced. I love ’70s superbikes and the GT, while not as out-and-out fast as its rivals, deserves to be included in the superbike bubble. That amazing wave of mid-range torque and the smooth, tireless engine are enough to ensure that. If you haven’t ridden a GT750 before, you really shouldn’t dismiss it until you have.
Suzuki marched to the beat of a different drummer with the design and concept of the GT750. When all around them (apart from Yamaha) were going down the four-stroke four route, they persevered with the two-stroke formula for a few more years, before ever-tightening emissions controls forced them to join the herd with their GS750 four-stroke in 1976. And, in doing so, they created a piece of motorcycling folklore – a genuine cult icon.
With its delightfully relaxing manners and individual character, the GT750 is unique. Smooth, quiet and with the broadest spread of torque of any of its contemporary rivals, it could have been tailor-made for the wide open spaces of America. In fact, it did enjoy an enormous and dedicated following all around the globe – and still does, nowhere more so than the UK, where the Kettle Club (thekettleclub.com) remains one of the liveliest and enthusiastic one-model owners’ clubs on the classic scene.
It may not be the fastest of the nascent superbike breed that emerged in the early ’70s, but it might just be the most accomplished all-rounder of its era.
‘A CLASSIC BIKE THAT WILL CRUISE AT 80mph ALL DAY WITHOUT FUSS OR RELIABILITY ISSUES’