A QUARTER OF ALL THE NEW MOTORCYCLES SOLD IN THE UK today are off-roaders of some kind. Once a niche product, dual-purpose machines that are usable off-road and at the same time ideal for long-distance touring are flying off showroom floors. Everything from Chinese 125s to mighty Triumph and BMW twins can be had, all kitted out for the dirt, and are selling well, often fitted with compact fairings and aluminium luggage – the two-wheeled equivalent of all those four-wheel drive Chelsea Tractors. Some of these chunky beasts will rarely touch anything but asphalt, yet they are still capable of eating dirt, should you so desire.
With the demise of BSA in 1973, it seemed that the end of big-bore dual-purpose off-roader was on the cards. Japanese manufacturers were building increasingly powerful big two-stroke semi-motocrossers, but for those who preferred big four-strokes on the dirt, it looked like it was all over.
At the same time, on the US’s West Coast, emissions regulations in California were becoming a major problem for manufacturers as legislators clamped down on ‘tailpipe emissions’. This had started in the late 1960s, and regulations that would particularly affect two-strokes were imposed on bikes bigger than 380cc in 1975.
Yamaha could see there was still some mileage in the four-stroke off-roader. Although its expertise then
