I had this pretty ancient Yamaha 650 twin festering away at the back of the garage. An import from America, the custom version, which with 81000 miles done had become so rattly that I decided to store it away and ride something else. That something else turned out to be an exceptionally pig-like CB900. Last year this most dubious device had ruptured its crankshaft which led in quick order to a seized back wheel. I crawled away from the wreckage and swore never to buy another bloody Honda.
The insurance was only third party and the bike such a write off that I didn't even bother digging it out of the ditch where it had ended its life. That left me destitute with no option but to sweep away the accumulated cobwebs and pull the XS out of its hiding place. Not being entirely stupid I had covered the Yam in grease and filled the engine with oil, so I was hopeful that it would start up.
New plugs, new points, new HT leads, new battery, new coils, new ignition wiring and about 2000 kicks later I was still swearing my head off at the dead as a dodo motor. Further investigation revealed that the handlebar on/off run switch had corroded, so once the wiring was sorted to eliminate it I at last had a motor that was grumbling away in characteristic, chuff-chuff-chuff, vertical twin fashion.
The disc brakes had welded themselves together with corrosion. The tyres had perished. The chain was more rust than metal, which went for the silencers as well, non original cut-offs that gave a healthy bark before and now traumatised the whole neighbourhood.
Rust had broken out where I'd previously touched up the frame and had also filled the petrol tap filter, which I suppose was better than filling the carbs! Other nice touches were a seat base that had all but disappeared in the brown plague, cruelly pitted forks and cast wheels that were bright white in alloy corrosion.
The list might sound bad but with a garage full of junk, a few tins of various cleaners and paint, and a degree in bodging I sorted out the worst of the problems. I never did get the rear brake to work properly but the twin discs out front, once dismembered and cleaned up, made up for that.
Out on the road, top speed was a mere 80mph, acceleration stately and vibration mind numbing. There was obviously something seriously wrong with the engine, probably the pistons because as far as I knew it had never been rebored! Still, the bike would potter along in top, once the multitude of false neutrals had been overcome when changing up the slow and clattery gearbox, at 60 to 65mph with all the charm of some vintage motorcycle.
The chassis greatly added to this impression. The original XS-2 had always been a bit of a wobbler. The even heavier XS650 was OK until everything let loose, when it was even worse. The Custom version was no better, but at sub-70mph speeds, when the mild chop riding position was tolerable, the bike felt planted on to the road with great assurance. This was mostly illusion, however, for the part worn Roadrunners I'd fitted would let the back wheel step out with sudden and terrifying violence.
Only quick reactions on my part saved me from a dose of gravel rash. The old chain I had dug out wore at an incredible rate, adding to the unpredictability of the gearbox, needing adjusting every 50 miles and links removed every 600 miles. The twin carbs were still quite miserly in their delivery of fuel to the engine, the old horror show still giving 50mpg regardless of the degree of throttle abuse.
All that could be said for the bike in this state was that it was rideable and looked OK from a distance. It also had much more street credibility than the C90 which had also been slung to the back of my garage as a reminder of how far I had come and how far I could sink! We did 7200 miles before anything terminal occurred. Even then the old duffer got me home on one cylinder, 25 to 30mph all the way.
A sudden influx of money meant I could buy another machine but for sentimental reasons I decided to renovate the Yamaha's engine. In fact, I ended up having a 840cc kit fitted with the wildest camshaft available. There are cheaper ways of committing suicide. The crankshaft was still OK but the engine needed a new tensioner and camchain, just to be on the safe side.
The XS650 engine is basically a very tough unit which can take the power of the increased capacity. What no-one pointed out to me was that it would be accompanied by a much bigger increase in vibration. It became immediately apparent why Norton had to isolate their similarly sized Commando engine in rubber mounts. As soon as the motor fired up with a throaty roar I was aware of the whole chassis blurring away under me.
With high compression pistons, it had taken all my weight and energy just to turn the motor over and about ten completely exhausting kicks to ignite the fires, so at first the vibes were welcomed as a relaxing massage to my knackered muscles. That feeling soon faded away when I accelerated up the road.
The engine roared off with loads of torque from tickover but shook so viciously that there was no way it could be used past 4500rpm. The mirrors were useless, the bars couldn’t be gripped properly and my feet kept sliding off the footrests. After five miles on the fearsome beast I couldn’t see clearly, my watch had stopped working and one of my fillings fell out, which left me sweating with the sheer agony of an exposed nerve.
After an emergency session at the local dental hospital where I was training fodder for a first year dentist with sadistic urges - why I had to get the one ugly harridan when there were lots of black stocking wearing nubiles around, I don’t know - I came back to the XS full of dread and injunctions to keep it below 3000rpm.
Riding home I forgot all that when in a race with an XS1100. I roared through the city centre, the revs in the red, the Custom leaping every which way in between cars, the whole deal taking on a surreal feel as my vision started to go first to double and then triple and then... then, there was a horrible crunching sound both in the motor and my mouth. The engine seizure was simultaneous with the new filling promptly falling out of my tooth. | was still insulated from the pain by the injection and, anyway, too concerned with pulling in the clutch whilst wrestling with the handlebars when the bike was in full skid mode.
We came to a graceful halt after battering the sides of three cars and giving a canine a whack on the head with the front wheel. The owner of the dog was more outraged by this abuse than the cagers. I was the centre of much irate shouting until the plod turned up. They weren’t much kinder to my traumatised soul but refrained from getting physical when I was able to produce all the relevant documents to show I was 100% legal.
I had the tooth pulled out this time, which left me with a mouth full of blood for several days. The XS was brought home and found to have the con-rods poking out of the crankcases. Further investigation revealed that the oil pump was full of crud, what had been a marginal but sufficient flow for the stock engine under the new forces of the tuned motor turned out to be entirely inadequate. The gearbox looked like it had been attacked my a demented gorilla wielding a pick-axe, so few were the teeth on most of the gears and so bent the selector forks.
The crankshaft was a mangled bit of metal wreckage. The cylinder head was OK apart from the fact that the cam lobes had disappeared and there was enough slop in the bearings to make a Honda G5 owner envious. The moral of all this is if you do any tuning work you have to check that the rest of the engine is in perfect working order.
The front wheel was bent, the forks twisted and various potentially expensive bits broken. My insurance was again minimal, I would probably be banned by them, anyway, after they received the claims for damage to three cars. Not to mention the fact that the dog owner was claiming huge veterinary bills and threatening to sue me for turning him into a nervous wreck, now afraid to go out of the front door with his bandaged mutt in case another crazed motorcyclist tried to run them down.
Good XS650 motors are so rare that there was little point trying to find one that I could afford. It was time to get really desperate and dig out the C90. The Yamaha XS650 was one tough cookie in its day, but that day is long past and most of them are now on the way to the knacker’s yard. If you find a good one by all means buy it, but don’t bother trying to tune it - just not worth the hassle.
Doc