Monday 28 February 2011

Yam XJ/XS Big Fours

How to blow up an XS1100. Not easy. Not when it was one of those bikes. You know the kind. One owner, always immaculately maintained and only 14000 miles in nine years. Winters? It was hauled into the house! When I turned up to view the Yamaha I was gobsmacked. Looked and sounded like brand spanking new.

It was much easier to fall off the XS rather than blow its motor. Mainly because the dopey bugger had left the suspension stock. The XS had 550lbs of ill-distributed mass. On soggy suspension it took merely an ill-judged bit of throttle work in corners to get it coming apart at the seams.

The direct connection to the motor's power and the shaft final drive gave a very jerky ride. That alone sufficient to upset the chassis in the bends. Further exploration of the bike was deemed likely to be highly suicidal. At that point, no way I could abuse the motor's 95 horses.

The one other area where time hadn't been kind to the bike was the braking. The discs were probably crap from new - it was that era of machinery. A visit to the breakers was in order. A very late XJ900 front end was hardly state of the art but it went on with a minimum amount of hassle. Cost a hundred notes, the old stuff part-exchanged. The breaker found me a pair of R & R shocks for forty quid, went straight on.

The back end was very stiff, the front still a bit soft. But at least the massive shuffling of the rear end was obviated. The front bounced around a little on fast exits from bends but I could control it with a bit of muscle on the bars. I liked the riding position, lacked the extremes of the replicas.

In second and third I was able to wind the throttle all the way open. The exhaust had a manly roar that went ballistic when the red-line was crossed. At low revs the engine felt a bit tractor-like. Then it smoothed out as the power and torque poured in. But come 6000 revs the secondary vibes ruled supreme. It's a big old straight four in the old fashioned mould. You get what you expect - a certain amount of violence accompanying the headier reaches of the power band.

Being vicious by nature, I held the throttle fully open in third on a long straight. By the time the ton had come up on the clock, my hands and feet were threatening to lose their nails! And my knees, where I clamped them on the big petrol tank, were tingling away. Were I a mechanical sophisticate I would've immediately backed off in deference to engine longevity. But I'm not, wanted to see if I could blow the motor in short order. I soon coped out. Whilst it felt far from bullet-proof, when my eyesight began to blur I knew it was going to win out. At least for that day.

I soon added a hefty fork brace to the front forks. Still not perfect, but every little bit helps. Now able to run flat out in fourth, the taller gear mitigating the secondary vibes. Hurling the XS through 120mph curves was fun. Kind of. The chassis felt extremely nervous, as if it was going to let loose at any moment. A few singular twitches of the handlebars gave me an idea of the violence that was hidden within the chassis.

Top gear runs were limited to 130mph - plenty more power to come but the speed wobble that coincided with that velocity was well wicked. The first time it happened, slammed the throttle shut and it faded away. Tried the same trick on the second wobble and it went totally wild. Had to wind it open again! Soon became clear that the bike's biggest trick was its total unpredictability!

After some experimentation, I found it was very susceptible to the front tyre pressure - out by as little as 2psi it could go very vicious. Even perfectly set, on newish tyres, the speed wobble didn't go away but it was more or less controllable. The best way to fight back was to gently loosen one's grip on the bars. Let the wobble die down of its own accord. Given the upright riding position, the lack of ultimate speed was no great loss.

One fun thing to do with XS11's is to take a pillion out and get the bike to do a speed wobble. Even more fun if he's a cager rather than a hardened biker, though even one of those got off the bike all weak kneed! Must've put at least half a dozen people off motorcycling! Not surprisingly, these fun and games soon led to chassis bearing demise. The bike not safe above 30mph, but easily fixed.

Because the big engine wallowed in torque, most of the time the revs weren't excessive. Hence 45mpg. Not bad for such a heavy old bruiser. Oil consumption too moderate to note. Tyres about 4000 miles, brake pads 6000 miles. Not too heavy on the running costs, at least compared to modern iron.

Back to how to blow up an XS11. With 48,400 miles on the clock the bike developed a heavy oil leak from the clutch cover. Coincided with a mad London to Land's End and back dash. I really thrashed the Yam, had to keep up with a couple of bro's on GPZ900's. Within 30 miles of London, gave the old girl a flat out blast in third. Grinding secondary vibes reached new levels of intrusion. There was a huge bang and a locked up back wheel.

By the time I braved the clutch lever, the back tyre was down to the carcass! Basically, the engine had lost all its oil and destroyed its crankshaft. The bearings on the latter are rumoured to be a bit dodgy after 50,000 miles. No real excuse for such neglect but for some strange reason I was sporting a fierce grin!

By the time I'd arranged for the XS to be returned to base I was totally pissed off with it and let it go for a mere 100 notes. The next bike was an XJ900, not a particularly nice one. But at 600 quid for a 34000 miler I couldn't really complain. Felt a bit constipated after the 1100 but a bit of throttle work soon had me grinning from ear to ear.

The XJ900 isn't actually viewed as a sweet babe with regards to handling. But it at least made a passing stab at weight distribution and steering geometry. After the big Yam it felt like a middleweight. Unfortunately, the first time I went over 120mph it speed wobbled just like the XS. What is it with these big Yamahas?

After much carnage, involving three lanes of highway, it pulled out of the tank-slapper. Sailed along with a suspicious sereneness. The problem wasn't intrinsic to the XJ, even if the early ones had a terrible reputation for speed wobbles. No, the problem was the Avon rear tyre that had cracks in it! Cold meat!

Once a new set of Michelins were fitted the bike would purr up to 135mph! Well, not purr exactly, the engine still rough and ready. Compared to the XS1100 it was rather sophisticated! It did have a rather harsh buzz at 90mph. Rather inconvenient as I considered this a reasonable cruising speed. I could change down a gear, but then the motor seemed a bit frenetic. The ton was smoother, but the plod rejoiced.

The braking was similar to my modded XS. Good for most of the time, could catch me out in the wet and didn't like being hammered from 130mph. Too much judder. Oddly, the calipers were much more short-lived than the ones on the XS. The calipers seized up every 6000 miles, or so. They needed new seals and a rigorous clean up. I was using EBC rather than Ferrodo pads, maybe the former were churning out more asbestos debris? I only thought about this in retrospect...

The bike lasted for 28000 miles, when the top end began to smoke heavily. A few miles later, the bottom end was knocking clearly. Probably down to my not changing the oil for 10,000 miles. Before it seized, I traded in at a local dealer. The new bike an an import Yamaha XJ750. Hey, these big Yams get to you in the end.

The 750 was 10hp down on the bigger four's 90 horses but weighed the same, just under 500lbs. It seemed more stable and the relative lack of top end urge meant it didn't speed wobble. There were plenty of back end weaves, down to fairly weak shocks. I wasn't too worried as they never developed into anything nasty. Even with more than a 100,000 miles under its wheels they never got any worse; worn as much as they were going to wear.

One problem I hadn't experienced before turned up - poor starting and cutting out. Especially in the wet. The shorty front mudguard was rapidly swapped for something more useful but made no difference. Nothing's that easy, is it? After much poking away at things, I decided that the coils were substandard. An XJ900 set from the nearest breaker sorted that. Hey presto, good starting and no more cutting out.

A leaking carb bowl due to a faulty float valve was next to intrude. Natch, it was one of the centre carbs, requiring massive disassembly of the bike to fix! Took three attempts to get it to work properly.

The clock read 49000 miles, the logbook had seven owners. Explained the rather worn state and constant need for fettling. A series of fast wearing chassis bearings followed by seizure of the front calipers soon had me tearing my hair out.

The engine needed undue revs to make it shift. Waste of time to use it below 6000 revs, 7000rpm better still. Come eleven grand the vibration went into a real grind; worse yet than the XS1100! But most of the power had done a runner by 10,000 revs so really not worth the effort. Unless, like me, you had a sadistic bent!

The gearbox was the worst I've yet to experience on a Yamaha. Took me 5000 miles before I got the hang of it. The best that could be said for it was that it never got any worse as the mileage piled up. Despite the early hassles and the thought that it was surely due for a rebuild sometime soon, I managed to get 60,000 miles out of the bike. And was still able to sell it.

This was surely down to the fact that the gearchange became impossible if I didn't do the oil changes every 500 miles! This is the simplest way of getting good mileage out of an old Jap. The valves and carbs were done every 10,000 miles - they probably needed it more often but I didn't need the hassle.

So goodbye XJ750, hello a totally outrageous beastie - a turbo XJ1100T. An extremely rare machine, the importer wasn't sure if it was a stocker or an American special. Someone with a sick sense of humour had turned this out with a mild custom look and then hastily added an handlebar fairing. The dealer reckoned 125 horses and I wasn't going to argue with that!

Figure about 600lbs. At very low speeds this was a very heavy motorcycle but with 25mph or more on the clock it didn't need too much effort on the wide bars. High speed corners, though, needed lots of muscle as the bike had a front end bias that wanted it to keep going straight on. A real joy when the turbo power blasted in!

Ah, that turbo! There was a slight lag, but it just seemed to intensify the blast when it went down. Jerked my whole being and nearly gave me an out of body experience. Great fun on the straights but you didn't really want to play with that power coming out of the bends! Not unless you liked to feel a chassis go all hinged in the middle and rejoice in playing chicken with oncoming cagers or walls!

Not a very practical machine. I was plain frightened of riding it in the wet! The brakes were very harsh, too. Less than a month after buying it, it was sold at a nice profit. What next? An XS1.1, of course!

Brian Williams