Three distinct philosophies. Three icons of the 1970s. As Iconic Auctioneers prepares for its Shuttleworth 2026 sale, we are taking a closer look at a trio of motorcycles that defined their respective categories. From the Grand Prix pedigree of the Yamaha TZ350 and the liquid-cooled engineering of the Suzuki GT750J, to the genre-defining performance of the Bultaco Sherpa T 350, these three bikes exemplify the quantum leap in motorcycle technology happening in the 1970s.
1978 Yamaha TZ350
The Yamaha TZ350 was the definitive tool for the privateer racer of the 1970s. It was a production racer available over the counter, offering Grand Prix levels of performance to anyone with the funds to secure a crate. While factory teams focused on complex four-cylinder engines, the TZ350 relied on a simplified, lightweight philosophy that allowed it to routinely punch above its weight class in open-displacement events.
The heart of the 1978 ‘E’ model is a 347 cc liquid-cooled parallel twin utilizing piston-port induction. It was a refined iteration of the earlier 350 cc designs, featuring 34 mm Mikuni carburetors and a Hitachi CDI ignition system. In race trim, this engine produced roughly 60 horsepower at 10,500 rpm—a narrow but potent power band that required a six-speed close-ratio gearbox to keep the machine on the pipe.
The chassis was equally purposeful, built around a twin-loop steel frame that prioritized lightness and rigidity. By 1978, the TZ had fully adopted the cantilever rear suspension system, which utilized a single shock absorber mounted beneath the fuel tank. This setup, paired with 35 mm telescopic front forks and a twin-piston front brake assembly, allowed the 250-pound machine to out-corner and out-brake much larger 500 cc and 750 cc competitors.
This particular 1978 TZ350, listed with Iconic Auctioneers, is fresh from a private collection and looks to have all the right pieces. It’s neither over, nor underrepresented—wearing a simple white livery with red stripe and blue roundels that many sported around the ’78 timeframe. The machine was previously used as a backup for a local racer, and a few scrapes are visible on the pipes and bodywork. That said, the bike still looks correct and presentable. The cockpit remains focused and functional, featuring the original-style cable-operated controls, a 14k tachometer and an analog water temperature gauge.
What remains unclear is why the bike is listed as a G, since the 1978 model would be designated TZ350E. Visually, the carburetors appear to be the F and G models’ larger 38 mm Mikunis, but the indicated redline on the tach matches the E model’s 10,500 rpm.
Nitpicking aside, we’re still looking at a lovely usable piece of Yamaha racing history. It represents the final evolution of the piston-port TZ series before Yamaha moved toward power-valve technology in subsequent years. For a collector or vintage racer, this machine offers a direct link to the era of the giant-killer, providing a raw, mechanical experience that modern electronics simply cannot replicate.
Pre-Auction Estimate: £6,000 - £8,000 [$7,920 - $10,560]
1972 Suzuki GT750J
The 1972 Suzuki GT750J arrived as a direct challenge to the air-cooled supremacy of the early 1970s. While Honda and Kawasaki were banking on high-revving four-stroke fours and volatile two-stroke triples, Suzuki took a more sophisticated route by introducing Japan’s first liquid-cooled production motorcycle. Earnest and massive, it earned the ‘Water Buffalo’ nickname in the US and the ‘Kettle’ in the UK, signaling a shift toward grand touring capability rather than outright hooliganism.
The technical core of the GT750 is its 738 cc three-cylinder two-stroke engine. By utilizing liquid cooling, Suzuki was able to maintain tighter tolerances and more consistent operating temperatures than its air-cooled rivals. The engine produced a smooth 70 horsepower, delivered via a constant-mesh five-speed gearbox. Unique to the early models was the Suzuki Recycle Injection System (SRIS), designed to burn off residual oil in the crankcase to reduce the characteristic two-stroke smoke, making it one of the most refined multi-cylinder machines of the era.
As a first-year J model, this machine possesses specific mechanical details that vanished in later iterations. It features the distinctive 3-into-4 exhaust system, where the center header splits into two smaller mufflers to maintain symmetry. Most notably, the J-model utilized a massive double-sided, twin-leading-shoe drum brake at the front—a complex piece of period engineering that was replaced by dual discs in 1973. The radiator was also tucked behind a prominent chrome guard and equipped with a cooling fan, a rarity for any motorcycle in 1972.
The example heading to the Iconic Auctioneers Shuttleworth Sale is a UK-supplied GT750J finished in the iconic Candy Jackal Blue. It retains the original-spec drum brakes and the specific J trim that collectors prioritize. With 16,878 miles on the odometer, the bike has undergone a comprehensive restoration to bring its brightwork and paint up to concours standards while preserving the matching-numbers integrity of the frame and engine.
Every detail on this GT750J reflects the touring-focused engineering of the early seventies, from the high-rise handlebars to the original-style instrumentation. It is a significant piece of Japanese history that marks the moment water cooling moved from the racetrack to the showroom floor. For a collector of early seventies triples, a first-year Kettle in this condition represents the high-water mark of Suzuki’s two-stroke development.
Pre-Auction Estimate: £6,000 - £8,000 [$7,920 - $10,560]
1978 Bultaco Sherpa T 350
The Bultaco Sherpa T is the machine that single-handedly ended the era of heavy British four-strokes in observed trials. Before the Spanish invasion, the sport was a game of momentum and massive flywheels. That changed in 1964 when Sammy Miller collaborated with Francisco Bultó to develop a lightweight two-stroke prototype. By the time the Model 199 arrived in 1978, the Sherpa T 350 had reached its most refined state, representing the final pinnacle of twin-shock trials engineering before the industry shifted toward monoshock designs.
The mechanical heart of the Model 199 is a 326 cc air-cooled single-cylinder two-stroke. Unlike its motocross cousins, this engine was tuned specifically for tractable, low-end torque. It utilized a heavy crankshaft and a Bing carburetor to ensure the motor could chug at near-stalling speeds without dying. This characteristic allowed riders to pick through technical rock sections with a level of precision that was previously impossible. The five-speed constant-mesh gearbox featured ultra-low internal ratios specifically spaced for the delicate throttle work required in high-stakes competition.
The 1978 model year marked a significant shift in trials construction, most notably with the introduction of the unbreakable plastic fuel tank that replaced the fragile fiberglass units of earlier years. The chassis was a lightweight steel cradle paired with Betor front forks and twin rear shocks, providing enough damping for big steps while maintaining a remarkably low center of gravity. Everything on the bike was purposeful, from the high-mounted exhaust designed to stay clear of water and mud to the narrow profile that allowed the rider to move freely during technical maneuvers.
This particular 1978 Sherpa T 350, heading to the block at the Iconic Auctioneers Shuttleworth Sale, is a standout example that has undergone a no-expense-spared restoration. Unlike many vintage trials bikes that have been merely tidied up, this machine was comprehensively rebuilt using approximately 75% brand new parts. The frame has been powder-coated and the bike is finished in the striking blue and white livery synonymous with the late-model 199A and 199B variants.
The mechanical specifics of the build are extensive, featuring two new wheels, a new exhaust system, tank seat, side panels, handlebars, cables and controls. The forks have been professionally rebuilt and the engine has been fitted with a de-compressor to assist with starting the high-compression single. With a new rear sprocket, chain, tensioner and guide, this Bultaco is functionally ready for a section or a collection. It represents a rare opportunity to secure a late-model Sherpa that has been mechanically refreshed from the ground up.
Pre-Auction Estimate: £3,000 - £5,000 [$3,968 - $6,614]
Source: Iconic Auctioneers
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