Yamaha · 1977–1979
The four-stroke thumper that took on the two-strokes — and won
In an era when the motocross world had gone completely two-stroke, two Swedish champions bolted a big Yamaha four-stroke single into a Husqvarna frame — and beat the smokers at their own game.
When Yamaha released the TT500 in 1975, in the tradition of the great British 500 singles, two motocross legends working for Yamaha of Sweden saw its potential: Torsten Hallman, four-time World Motocross Champion, and Sten Lundin, twice a World Champion. They took a Swedish Husqvarna frame, modified it to swallow the big Yamaha thumper, and tuned the engine from a standard 30 hp to over 50. The project took the first letters of their names — HL — and the engine's capacity: HL500.
Hallman persuaded Yamaha that racing the machine would make fine publicity for the road-going XT, and handed the bike to fellow Swede and two-time World Champion Bengt Åberg. Åberg campaigned the HL500 in the 1977 500cc Grands Prix, winning in Luxembourg and finishing ninth overall — the first World Championship points scored by a four-stroke in an MX Grand Prix in a decade.
Yamaha built roughly 200 factory replicas in 1978 and a further 200 in 1979 — just 400 machines in total. Genuine examples are extremely rare today, and the HL500's giant-killing run is remembered as the spark that kept the four-stroke flame alive through the two-stroke years.
The HL500 was only one of the machines to spring from Yamaha's big single. When the XT500 dual-purpose model appeared in Yamaha's 1976 line-up, few could have guessed that its large single-cylinder engine would go on to found two of the marque's most enduring names — the road-going SR and the desert-bred Ténéré. Both traced their roots to the deserts and wide-open spaces of the United States.
Through the 1970s, young riders on the American West Coast had taken to enduro — hours spent crossing the country's vast plains and deserts. Yamaha sold only two-strokes at the time, and the market was calling clearly for a four-stroke. The answer was the enduro-focused TT500, designed, developed and launched alongside its dual-purpose sibling, the XT500. What competitors wanted was strong, usable torque, and a large-displacement single delivered exactly that. The first desert prototype was shipped to the U.S. for testing — unusual at the time, as machines were rarely proven in the very conditions they were built for. Riders put it through some two-and-a-half times the normal amount of flat-out running; the punishment pushed pistons and connecting rods to breaking point, letting Yamaha's engineers find every weakness and build in the reliability the bike would need.
The XT500 found an especially devoted following in France and Italy, where it was ridden in beach rallies and the desert rallies of West Africa. An XT500 won the very first Paris–Dakar Rally in 1979, and the second as well, quickly making it the rally machine to have. As the Paris–Dakar became an FIM-sanctioned event and more manufacturers and teams piled in, the racing grew fiercer, and outright top speed became the key to winning. The XT500 evolved into the four-valve XT550 and then the XT600 Ténéré, carrying a huge 30-litre tank. "Ténéré" is a desert spanning more than 400,000 square kilometres across Niger and Chad; from the 1980s the name came to stand for Yamaha's appetite for crossing such country, and remains an icon to riders and fans alike. Later came a five-valve engine and fuel injection, and the XT660Z Ténéré carries the line on today.
The road riders wanted their share too. With the XT500 selling well, calls grew for a street bike built around the same engine, and in 1978 Yamaha answered with the SR400 and SR500. The XT's engine formed the basis, reworked in detail for the road. A slim chassis gave honest, straightforward handling, and the single's steady beat won buyers over. SR500 deliveries to Europe ended in 1995, though it keeps a cult following in Germany to this day; the SR400 stayed in production far longer, sold across Europe, Australia, the U.S., Thailand and Japan. Its appeal lay in timeless looks and the tangible pulse of the engine beneath the rider.
More than once Yamaha considered ending SR production. Yet in a world of ever more complex machinery, the SR's simple single and classic lines were precisely what gave it its character and its place — and that character, the company decided, was an asset worth keeping. The styling barely changed from the first bikes of the late 1970s, and SRs can still be found on the road today.
Photographs to be added.