The Ducati 750 GT

For a relatively small and financially struggling company such as Ducati to get things so absolutely right in the early 1970s was an amazing achievement (and a hugely significant one, too). It could be argued that, of all the hundreds of models that Ducati has produced since the marque’s birth more than half a century ago, the model that began the V-twin line is the most important of all. As well as launching Ducati’s superbike range in such style, and leading to so many other great roadsters, the GT was also the basis of vital racing success, most notably Paul Smart’s famous Imola 200 victory in 1972.

The birth of the L-twin
The Ducati 750 GT was very much the work of Taglioni, who had joined Ducati from Mondial in 1954 at the all-powerful post of chief designer and technical director. He was just 34 years of age. As an engineering student at the University of Bologna six years earlier, he had produced a design for a 250cc, 90-degree V4 with cylinders running in line with the bike. At Ducati in the early 1960s, after revitalizing the company with successful singles including the 100cc Gran Sport, he adapted this V4 layout to create the mighty Apollo, which never reached production largely because its 1,260cc engine was too powerful for contemporary tires to handle.

Ducati had long been aiming to produce a twin, but not with cylinders in a vee. The firm had raced parallel twins in the 1950s, and in the mid-1960s developed a succession of larger-displacement parallel twins, with the aim of producing a roadster to compete with the dominant British models. But although a 500cc twin was displayed at the Daytona Show in the U.S. in March 1965, neither that bike nor the 700cc prototype that followed two years later reached production. Meanwhile, Honda launched the CB450 twin, whose arrival helped ensure that the Italian firm’s dealers in the vital U.S. market met an improved 500cc Ducati parallel twin with little enthusiasm. The project was abandoned.

By this time Ducati was in financial trouble, and in 1969 the firm was taken over by the Italian government. Honda had recently introduced the CB750 Four, and fortunately Ducati’s new management team not only saw the need for a 750cc model but also realized that it needed to be something special rather than another parallel twin. Taglioni, whose stated design aim was “simplicity, carried out to its ultimate extreme,” adapted his earlier V4 layout to create a V-twin, or more accurately an L-twin, that was essentially two 350cc singles on a common crankcase.

Ducati worked fast. Taglioni’s design was finished by March 1970; the first engine underwent testing four months later, and it was so impressive and trouble-free that by September a complete bike was ready to be unveiled to the press. By June 1971 it was in production. Called the GT750 (also often referred to as the 750GT), it incorporated a few changes from that prototype press bike including flat bars instead of clip-ons, a 280mm (11in) Lockheed single front brake disc instead of a Fontana drum, 30mm (1.18in) Amal Concentric carbs instead of Dell’Ortos, and a reshaped tank and seat unit.

As well as being distinctive, the engine layout had the obvious advantages of small frontal area and low center of gravity. The 90-degree vee angle gave perfect primary balance, while Taglioni’s decision to raise the front cylinder by 15 degrees from horizontal allowed good cooling to both pots while also helping exhaust routing and ground clearance. The effect of the L-motor’s inevitable length was minimized by the way the front cylinder head fitted between the downtubes of the tubular steel frame.

Like the factory’s well-proven singles, the V-twin featured bevel drive to a single overhead camshaft, wet sump layout, and an integral five-speed gearbox. The 748cc engine used conventional coil springs to close the intake and exhaust valves instead of the desmodromic layout (where rocker arms open and close the valves) that Taglioni had already introduced on some racing singles, and produced a claimed 60hp at 8,000rpm. At 185kg (407lb) dry the GT750 was 15kg (33lb) heavier than the earlier prototype, but considerably lighter than the wet weight of 186kg (499lb) for the 67hp Honda CB750 Four.

Power-to-weight on the road
That gave the Ducati 750 GT a very impressive power-to-weight ratio back in 1971, and more than three decades later it is still enough to make this near-perfect example great fun to ride. Not that the bike performed flawlessly on my test, at least at the start.

The cold engine needs several kicks before it reluctantly fires up, though the glorious mix of rustling mechanical sounds meant I soon forgave it once it did come to life. Maneuvering at slow speed highlights the lack of steering lock, and the gearbox is initially very stiff, as well as providing an unfamiliar one-up, four-down pattern for my right foot.

But after just a few miles the engine has warmed up, the gearbox is working fine, the sun is gleaming off that shapely tank (whose high-quality paintwork doubtlessly surpasses the notoriously poor original finish), and the Ducati is running so well that it is amazing to think that any bike, let alone a first attempt, could have been so good all those years ago. That 60hp claimed maximum was doubtless a rather optimistic figure, and this engine can’t match the midrange grunt of the bigger-bore V-twins that followed it in the 1970s. But the GT still accelerates with plenty of enthusiasm, its straight-line performance emphasized by the fairly upright riding position that is still sporty enough to allow a comfortable crouch into the wind at higher speeds.

In best Ducati V-twin fashion the engine is smooth enough to be pleasant throughout the range, but has enough vibration to give it an involving feel. This engine has been recently rebuilt so I didn’t rev it to the start of the red zone at 7,500rpm, let alone the proper redline 500rpm later. But that’s fine, because the valve-spring unit is at its leisurely best when short-shifted, and is happy to keep the bike cruising at a relaxed 70mph — and more. Fully run-in and with the rider’s chin on the tank, the GT was good for a genuine 125mph, and that made it one of the world’s fastest bikes in the early 1970s.

And its handling, especially at high speed, was notably better than that of heavier Japanese multis such as the CB750, Suzuki’s GT750 and Kawasaki’s 500 and 750cc air-cooled triples. Right from this model, its first Superbike, Ducati hit on the format of relatively lightweight, minimalist but rigid frame and fairly firm suspension that would make the marque’s name a byword for handling excellence. It was resolutely stable at high speed. And although the blend of conservative steering geometry and 19in front wheel means it requires a fair bit of input, it was light enough to respond quickly when I needed to change direction on a narrow and twisty country road.

This bike’s ever-reliable Pirelli Phantoms also helped by being sticky enough to make good use of the GT’s ground clearance, which is generous despite the reasonably low-set and comfortable footrests. The only chassis part that really felt dated was the front brake, which is a bit wooden and lacking in power. The other fork leg has lugs for a second disc, but Ducati never fitted one to the GT, though the factory did introduce a few updates on later machines, including this bike’s center-axle front forks (instead of the original leading-axle design), and the addition of an electric starter on the last bikes to leave the factory. There was also a GT750 USA version, with higher bars, and a police version with a windshield, saddlebags and a single seat.

Production of the Ducati 750 GT ended in late 1974, when it was replaced by the 860 GT, with its controversial angular styling. By this time the 750 had been hopped-up to create the more aggressive 750 Sport, with its clip-ons, rearsets and optional half-fairing; and the even racier 750 Super Sport, with its desmodromic valve operation and single seat, inspired by that famous Imola victory in 1972. Ducati’s V-twin range was well under way, and one of the great motorcycling dynasties had been established.

Classics reborn
Years later, those old Ducati V-twins are in the limelight again, as the Bologna firm honors them with its new SportClassic range. Perhaps it’s appropriate that while the more glamorous Sport and Paul Smart models were launched six months ago, the GT1000, inspired by this less celebrated original V-twin, was held back until now — but looks to be the best seller of the three. If ever there’s a classic Ducati that deserves modern recognition, it’s the unsung GT750 that began the line in such brilliant style. MC

Retro revisited: GT1000 SportClassic
Years produced: 2006
Claimed power: 92hp @ 8,000rpm
Top speed: 135mph (est.)
Engine type: 992cc overhead cam, air-cooled 90-degree V-twin
Weight: (dry) 185kg (407lb)
Price:  $9,995
MPG: N/A
Ducati’s first SportClassic models, the Sport 1000 and Paul Smart, are great bikes. They combine retro styling with modern engine and chassis performance in a way that makes them hugely appealing. Trouble is, anyone old enough to remember the classics on which they’re based is likely to get uncomfortable very quickly aboard bikes whose low clip-on bars give a viciously racy riding position.

The new GT1000 — which owes its look to the original early-Seventies GT750 and has a similarly high-barred riding position — is a much more relaxed and roomy machine. The key elements of tubular steel frame and air-cooled, 90-degree V-twin engine are naturally retained, albeit an engine (borrowed from the Multistrada and Monster, and almost identical to that of the other SportClassics) whose right side is largely obscured by the belt drive (rather than bevel shafts) running to its single overhead cams.

I was slightly disappointed that the new GT doesn’t look more like the old one. Its gas tank is larger and more rounded than the old 750’s flat-bottomed item, in particular, mainly due to the modern machine’s big airbox. But the GT1000 is well finished, and looks good in either red or black paintwork, the two colors currently on offer.

Ducati’s 992cc two-valve, V-twin powerplant produces 92hp at 8,000rpm, with lots of midrange torque plus a finely honed Marelli injection system. Inevitably the emissions-controlled GT1000 doesn’t sound as good as its forebear with its free-breathing carbs and pipes. But the modern twin-spark V-twin produces a pleasant note through its catalyst-equipped mufflers.

This SOHC desmodromic engine differs from the other SportClassic lumps in its black-finished plastic cam-belt covers, and its use of a wet instead of dry clutch; in traffic the clutch worked very smoothly. At low revs the engine felt slightly juddery, before smoothing nicely at about 3,500rpm. But that simply adds to the GT’s character, especially as the six-speed box shifts very cleanly.

Fuel-injection response is very crisp, and on the open road the GT cruises along with a pleasantly effortless feel, always seeming ready to respond thanks to its hugely flexible power delivery. The generous reserves of midrange grunt allow quick riding without need to approach the 8,500rpm limit. Top speed would be about 135mph, though you’d have to hang on tight.

For anything other than prolonged high-speed riding this bike is much more comfortable than the wrist-punishing Sport 1000 and Paul Smart models, helped by its broad and reasonably thick dual-seat. But the Marzocchi forks feel slightly vague when the front brake combo of 320mm (12.5in) discs and twin-piston calipers are used hard. And large bumps occasionally got the better of the Sachs shocks in back-punishing fashion.

Even so, handling is good. At 185kg (407lb) — identical to the original GT750 — the GT1000 is respectably light, and its combination of wide handlebars and reasonably steep geometry mean the bike can be flicked through tight bends at an entertaining rate; high-speed stability is well up to traditional standards. And there is plenty of ground clearance with which to make the most of the Michelin Pilot Classic tires, which grip well but lack the distinctive period look of Pirelli’s new-generation Phantoms.

In that and other respects, the GT1000 doesn’t quite project the Seventies feel of Ducati’s first two SportClassic models. But as well as being much more comfortable than those bikes, the GT performs very well and is also slightly cheaper than the Sport 1000, let alone the limited edition Smart. That makes it the sensible choice for most riders looking for a modern V-twin with classical Bolognese style.

Resources
Vintage Ducati parts
www.bevelheaven.com

Ducati Owners Club
www.usdesmo.com

Ducati
www.ducati.com/od/
ducatinorthamerica.com