Floating in amongst the myths and legends, in the margins of ’70s American racing culture, a strange hybrid briefly existed. Known as the Montjuich Class, it demanded motorcycles capable of surviving endurance tarmac battles while still delivering explosive standing-start performance. Half circuit racer, half drag weapon, these machines were conceived by Californian petrolheads who valued power-to-weight ratios as much as reliability. It was an arena perfectly suited to Yamaha’s two-stroke philosophy, and this 1971 Yamaha R5-B 350 by JETS Forever seeks to tell that fabled tale.
By the early ’70s, Yamaha’s lightweight twins were already troubling the established British order. The R5 and its descendants proved that displacement wasn’t everything, and the 350cc TR3RD endurance racer underlines the point. Compared to the torque-rich Triumph twins, Yamaha’s air-cooled two-strokes relied on revs, balance, and minimal mass. On fast circuits and long stints, that translated to less fatigue, fewer consumables, and lap times that punched well above their class. The Montjuich concept leaned directly into those strengths.
According to long-circulated paddock lore, Yamaha’s West Coast distributors explored a limited-run endurance racer tailored specifically for the American scene. Intended to blur the line between competition machinery and street legality, the so-called “Red Rocket” project was envisioned as a ready-to-race platform that could be ridden to the track, raced hard, and ridden home. Whether the idea was killed by cost, timing, or corporate caution is unclear. What is certain is that no production Montjuich Class Yamaha ever reached showrooms.
That gap in Yamaha history is what JETS Forever set out to address. Drawing on archived race data and period-correct factory references, JETS associate tech guru Tony Taysom undertook the task of building a 1971 Yamaha 350 TR3RD Montjuich Class machine as it might have existed. Working under the guidance of Jeff Duval, the project was treated not as a custom, but as a hypothetical factory prototype, one where every decision had to make mechanical and historical sense.
The chassis forms the backbone of that philosophy. Based on an OEM frame originally designed for lightweight endurance racing, it was race-modified and then painstakingly restored, with structural improvements kept deliberately invisible. The finish, a deep black with subtle red metallic flake, adds a modern edge without breaking period illusion, while restored Yamaha badges anchor the bike firmly in its era. Suspension duties are handled by a classic Yamaha lead-axle fork assembly and CR Suspension rear shocks, chosen for compliance and stability over long stints rather than outright stiffness.
At the heart of the machine sits a fully rebuilt 348cc air-cooled two-stroke twin. The crank, rods, and pistons were dynamically balanced, while the gas-flowed head feeds a pair of Amal Concentric MkII carburettors tuned specifically for endurance use. Rather than chasing peak horsepower, the emphasis was on tractability, throttle response, and thermal stability, qualities essential in a class where finishing was as important as outright speed. Power is delivered through a rebuilt OEM five-speed transmission, maintaining factory ratios that favour flexibility over aggression.
Braking and rolling stock reflect the same hybrid intent. Alloy wire wheels, 18-inch rear and 21-inch front, keep rotating mass low, while stainless spokes add durability. Modern Beringer racing brakes front and rear provide stopping power far beyond anything available in the early ’70s, yet remain visually restrained. Instrumentation is reduced to a Speedhut competition speedo and tacho, reinforcing the bike’s single-minded purpose and keeping the cockpit free of distraction.
Visually, the bike walks a careful line between restoration and reinterpretation. Image Custom Design replicated Yamaha’s period red and white livery, elevating it with candy metallic and pearl finishes separated by gold leaf pinstripes. Final assembly, tuning, and inspection were handled entirely in-house by Taysom and JETS chief tech Sean Reynolds, ensuring mechanical cohesion throughout. What stands today is not just a restoration, but a credible answer to a question Yamaha never officially asked: What if the Montjuich Class had made it out of California folklore and onto the road?
[ Jets Forever ]