Classic Motorcycle Mechanics

Design, launch and reaction to the Yamaha XT500


Yamaha’s XT500 first appeared at the 1975 21st Tokyo Motor Show. The big single was supposed to be dead and buried but the maverick Yamaha factory had pulled off an audacious coup. Acing Honda’s then largest four-stroke single, the XL350, Yamaha’s XT500C was a direct response to the USA’S Environmen­tal Protection Agency (EPA) and their drive to eliminate two-strokes. Yamaha carefully evaluated the outgoing British singles and had concluded that the motors were simply too tall and had thereby compromise­d ground clearance. Opting for a shorter-stroke and smaller flywheels delivered a physically smaller power unit. Eschewing a four-valve head the motor was designed to deliver torque, not all-out power. Still clinging to its two-stroke roots, Yamaha opted for a pressed up crank with full flywheels and a roller bearing big-end. Not everything British was ignored; Yamaha took a leaf out of Bsa/triumph’s book by using an oil bearing frame which neatly dispensed with need for an oil tank but there they differed from British practices. Two oil pumps were used; one to supply and one to scavenge. Elsewhere the bike borrowed heavily from establishe­d DT practice in both transmissi­on and chassis design. When the press got hold of test machines they loved them. Juicy slices of torque were available from 25005500rp­m which was where Yamaha had concluded maximum power should be; a winner straight out the crate. Although not perfect the bike won over critics and, predictabl­y, Honda and Suzuki were stung into action with larger capacity XL500 and all new SP370S respective­ly. Developmen­t of the Yamaha (of course) had to continue. Late in 1976 Yamaha revised the XT500C; stripped down it was offered as a semi-competitio­n version stateside called the TT. And when Swedish champion Sten Lundin got involved along with likeminded enthusiast­s a full competitio­n model was developed which was later sold to a select cadre of experts as the HL500, circa 1977. Yamaha was riding high and the successes just kept on coming with the first two places in the inaugural Paris-dakar Rally of 1979. A year later the XT500 bagged the top four places in the

same event and sales simply took off. Annual revisions kept the bike at or near the head of the field until 1982/83 when the 500 became a 550. Despite four valves and two carburetto­rs the all-new XT550 failed to grab the public and less than favourable reports did little to generate sales. With some cajoling by the French importer Sonauto Yamaha offered an XT600 special called the XT600 Tenere which was essentiall­y a replica of the Paris/dakar race winning bike. From that point on the big XT was back in the game and the concept lives on to this day with

machines such as the XT600R. Factor in the road going SR500 based launched in 1987 and its smaller

brother the SR400 which remains a current model and you’d be correct in assuming Yamaha was right to

challenge that early 1970s preconcept­ion; big singles had and still retain a rather rosy future!

“So, out on the road, what is the XT500? Well, it’s essentiall­y a Yamaha DT250 that’s been consuming huge quantities of anabolic steroids and turns that into FUN. It’s a two-wheeled legend.”

the bike is all about. It’s an easy bike to ride on Tarmac using little conscious effort and just the smallest input via the wide bars has it changing course. The oil-bearing frame is nigh-on bomb-proof and never gives cause for a second thought. Suspension-wise the bike is set up for comfort rather than enduro ability and that’s as it should be; most XTS were only ever taken off-road occasional­ly anyway. Braking is something of a mixed bag with decent feedback from the rod operated rear drum but a front that feels a little on the marginal side even allowing for bedding in. Yet this is how most trail bikes of the period were; fit a drum brake that’s great on the road and it’s unlikely to dump you on your ear in the rough stuff. And then of course you can always call on the engine braking to assist. We were able to give the Yamaha a brief taste of freedom via a dry farm track up a steepish hill. For dirt novice numpties such as muggins here it was fine, soaring up a reasonable gradient with ease. The bars and pegs are set up just fine for a standing ascent and that engine is superb in its intended environmen­t… well, up to a point anyway. With a wet mass of 150kg or nigh on 350lb it’s no lightweigh­t and anyone who used one of these in anger back in the day was either mad and hospital bound or pretty damn fit. Of course the bike did establish an enviable reputation for itself off-road but not without some serious weight paring and fettling. Post static shots the bike was extremely carefully ridden down the track (it someone else’s pride and joy after all) and again acquitted itself with flying colours in the hands of this self-declared dirt avoider. Here on an unstable and changing surface ranging from loose dry stones to muddy pebbles those anchors were just about perfect. And this is why period trail bikes were so much of a compromise. Summing up, the XT500 is a grand piece of kit and a refreshing change set aside from the late 1970s scrabble for ever-greater power and higher top speeds. To the lads who upgraded from a small Suzuki TS or a Kawasaki KE the XT500 was a logical, if ultimately intimidati­ng step change. For the older guard who had laboured with big British singles the bike must have seemed like an arrival from another planet.

 ??  ?? The blueprint for an amazing motorcycle, much copied to this very day.
The blueprint for an amazing motorcycle, much copied to this very day.
 ??  ?? Where the original was happy to be. Today, do you wanna ruin a minter?
Where the original was happy to be. Today, do you wanna ruin a minter?

Newspapers in English

Newspapers from United Kingdom