Now designed solely for the tastes of a continental market, it's easy to see how the XT has developed a long way from ‘its original concept. Today's incarnations, the XT600 and Tenere, have a much greater emphasis on styling and road orientation, yet still keep up the image of a big butch dirt bike. The fat tanks and electric starts haven't done much for off road ability, but the adoption of the twin choke carb and four valve head, along with constant chassis improvements, has ensured that the XT will remain a dirt bike for serious consideration by the big strong nutters.
All that torque combined with four stroke power pulses find traction where two strokes break loose and can get things moving incredibly quickly. As a trail bike it can get you into lots of trouble. So it's important to make sure everything's pointing in the right direction when you Go For It. Many's the XT rider who can tell you a horror story of what happens when you get too casual with one of these beasties.
Good old Feargus, one time member of our trail club, looped his brand new XT500D on its absolutely first day out. A handful of throttle soon got him up to an exciting speed. But a handful of brake just couldn't get rid of it quick enough, not as quick as the PE250 he was dicing with anyway. The PE stopped yards short, but Feargus and his XT launched off a huge mound like a Fireball XL5.
When it was all over, I was reminded of one of those tragic plane crashes on a Spanish mountainside. Bits of white plastic scattered everywhere. Control levers, broken glass, and just about everything that could break off was littered amongst the deep furrows the XT had gouged into the moor. The bars were bent down like clip-ons and the rear frame loop was turned up a good six inches - the seat and mudguard could only just be tied on with fencing wire. Naturally, the tank was BTF. Feargus was OK, apart from where his key had dug into his bum he couldn't sit down for a whole week.
Apart from the usual crash damage, there were one or two other problems common to early versions of the XT. Most annoying was the penchant for breaking the gear selector spring, usually leaving the bike stuck in the most inconvenient gear for the situation. You're unlikely to find this problem now, unless someone finds a low mileage (less than 5000 miles) example of an early model.
The XT also suffered temperamental starting when cold, hot or just warm. This is a fault that cursed every XT up to and sometimes including the six hundred. This is especially true if you fall off and the bike spends more than a couple of micro seconds on its side. There have been many theories as to the cause of this inconvenient and frequently embarrassing little quirk. But if anyone out there actually knows of a cure, for goodness sakes tell the world. Or if you're a devout capitalist, put a mail order ad in the magazines: Cure Reluctant Starting On Your XT - Be The First Kid On Your Block With The Big Yam That Fires Up Every Time.
Camchain and bore life seems at least as good as the other big Jap trail bikes. Although, it's as well to remember that the engine needs frequent oil changes to keep it in good condition - especially for the top end. Regular and effective maintenance is necessary to keep the engine running, but don't be misled by the bike's external appearance with trail bikes a few dents and scruffy paintwork are quite normal and unlike road bikes are not necessarily indicative of engine neglect.
It took six years before Yamaha finally made a few worthwhile improvements to the basic XT. The amazing thing was that people were still happily buying bikes that had remained unchanged since 1977. How did the XT manage to remain so popular off road when there were rivals a 1l00lbs lighter, that even if they lacked the ultimate power of the XT, still ‘had enough go to make life interesting?. Dare I mention character? A sort of legendary reputation for the sort of raw power that needed a super hunky motocross man to get the best out of it. In fact, that's still a main attraction of today's XTs and Teneres.
Helping to build this reputation, of a beast that could deliver the goods in the right hands, was European Yamaha importer Hallman. With a little financial backing from Yamaha and a competent rider, a competitive XT moto-crosser was fielded, which showed promise with a number of good finishes in the Grand Prix. Granted up close there wasn't much resemblance to the standard machinery, with its YZ forks and wheels, one-off frame and extensive engine mods. But when the HL500 (for such it was called) won the first motocross of the Luxembourg GP, any doubts about the off road potential of the XT were swept aside. What had been a steady trickle of heavy duty shocks and light weight swinging arms over the dealers counter, now became a raging torrent of high performance hardware, turning hundreds of XTs into balls-out moto-crossers and enduros. Big bore kits were popular for a short period around this time. The short period being about equal to the time taken for the high compression and usually overstressed engine to wear itself out.
We passed a few minutes in pleasant chat about the weather, the state of the economy, and whether or not O-rings chains would ever catch on. They pulled a few wheelies to demonstrate just how low was their low end torque. Lower than a snake's belly was the phase 1 believe they used. Hmmm. Next off, one of them decided to show me how well he could dig trenches. Up the side of a hill cum cliff that I'd been eyeing for a spot of abseiling. He did it very well until he missed a gear and over revved the engine - when he came down we all agreed the engine wasn't sounding too good. But we thought he could make it back, coasting down the hills. We were wrong. They hadn't gone twenty yards down the trail when the XT made a noise like a pig swallowing half a cabbage and called it quits. What value radical engine mods now, I thought. Missing gear shifts I had over revved my standard machine many times without screwing up the engine. Plain Jane and I continued on our way, feeling quite content to be just a couple of ordinary everyday types.
Those looking for more power at low revs and a better pick up from a closed throttle were better catered for when the XT550 finally came on the scene. The four valve head and twin choke carb (YDIS) shoved the max torque a fair bit lower down the rev band. But their main effect was to clean up the throttle response when suddenly opening the throttle at low revs. No more coughing, spitting back or hesitation. When you nailed that throttle the new 550 really sat up and took notice. The science behind the twin choke carb is incredibly simple. One small throat carb to run the engine efficiently at low revs when little air is required and a larger bore cuts in further up the rev band as more air is needed.
And for those who spend time on the tarmac, the XT featured a balance shaft to smooth out the vibes at high revs. It actually worked quite well, if you can hang on, 80mph motorway cruising was possible. Starting problems hadn't been entirely overlooked, but sadly the automatic decompressor was little more than a gesture. And many owners said they preferred the old style manual decompressor. At any rate, starting remained as unreliable as ever.
The only backward step was in the clutch department, where distorting and disintegrating clutch plates became a problem on the early five fifties. This is something to watch out for on low mileage used motorcycles. The all new 550 was also a better handler, which was welcome considering the ease crashed and extensively damaged. But unfortunately it didn't quite work out that way. While the new chassis gave a ride that inspired a lot more confidence on the dirt and there was more room for the rider to move around to influence his trajectory, the mass of the bike meant it still remained one hell of a handful. It didn't really matter that there was no more top end power (it was probably just as well considering the mess you could get into with the old bike's speed), but it was disappointing to find weight reduction amounted to little more than a few pounds (thanks, I suppose, to the huge twin carb, balance weights and heavier head). In fact, the difference in mass would rapidly disappear if you traversed a section of axle deep mud because the bike picked up most of the muck.
Another mixed blessing was the single shock rear suspension. This was a great improvement on the XT, but still left a lot to be desired. It was that old problem of Jap bikes of having inadequate damping. The bike was fine when used on the road, but as soon as it had to cope with the kind of bumpy terrain found on the average trail, the shock became all hot and bothered; once the damping started to fade, the bike had a disconcerting tendency to bounce you right off the bike at the next big bump.
Early in '84 the XT600 appeared, which was yet another step nearer to the stuff serious off roaders are made of. Vastly improved rear suspension, in the form of a vertical rising rate rear shock with ten inches of reliably damped travel and beefier front forks with eleven inches of travel. Combined with other YZ inspired bits and pieces the bike was a good match for the mud splattered mad men, and like them the bike looked every inch the part.
One of the most visible and most dramatic mods was the front disc brake, which because of the long travel forks could induce frightening levels of dive at the front end. But at least it didn't become water logged every time the. trail rider crossed a stream. With its new chassis and suspenders, and improved low speed grunt, the six hundred is a far better trail bike than the earlier attempts. The only problem for buyers of second hand bikes is actually finding one. They're not exactly common.
The TT version has even more low down grunt but still suffers from excessive mass when the going gets really tough, but it is significantly lighter than the stock model. Unlike the XT it came with plastic tank and dumped the electric start (which given the difficulties of starting the 600 if it stalls knee deep in some mud or water infested trail isn't such a good idea) and used lighter components wherever possible. It also simplified the lighting system to the bare minimum, which is fine until you try to ride in the dark for any distance. The TT is the rarest of the Yam big singles, has competitive weight against other big four strokes, is the best off road device and is very much sought after.
Not so competitive weight wise was the Tenere, with its bulbous tank and electric start. A response to great demand from the continentals, who wanted to be thought un peu crazy as they cruised along the boulevards in imitation of the true grit Paris Dakar Tacers, who everyone recognized as being terminally insane. They sold in their thousands. Long distance comfort on the Tenere has the usual trail bike limitations. Arms spread so that the body catches the wind like a sail, most of the body weight supported by the bum resulting in lower back pains after just an hour or so. But the suspension gives a comfortable ride and the OE trail tyres will survive for a good four to five thousand miles of use on the tarmac.
Trundling around in the South of France last summer, I discovered that Yamaha can still knock out the odd machine that can completely shag its bore in less than two and a half thousand miles. This was especially galling for my friend who had spent a 1000 miles very carefully running in his Tenere only to find that the motor sounded like a tractor engine when it was time to head for home (perhaps the bike just liked loitering in the sun as much as its rider). We found it difficult to believe that piston slap could get that loud. My friend would have probably heard it earlier if he hadn't ridden everywhere with a Walkman wired into his helmet. By the time we arrived back in the UK, the noise was loud enough to drown out Motorhead at full volume.
Between frequent oil top ups, the bike shattered the peace and rattled and slapped its way home sounding more and more like a Tiger Cub on its last legs. It took five months for the dealer to get a new barrel and piston. Give the dealer his due, though, he did offer to re-bore and fit an oversize piston and then fit the a when they arrived. But my friend was going abroad anyway, so he decided to wait.
The bike's done 30690 miles without problems. Big for the road, the XT series were great fun around town and for posing. The Tenere was quite useful for going touring, while any of the bikes had the old British bike attitude of being able to ride the bike you want to green lane on the road as well. On the dirt, unlike the Suzukis and Hondas, the XT excels with its low end power. You don't have to rev the balls off it just crack open the throttle and you're gone...
Malcolm Ingham