I had looked at a couple of Desmo 500 twins. There were not many about in this country as they never sold well. The first had been stored away, apparently since it was purchased, only having 350 miles on the clock. It was perfect... and worth every penny of the £5000 price tag, at least according to the owner. I didn't agree. The second, by way of contrast, was less than a tenth of the price and a total rat. I would not have been happy paying fifty quid, such was its terrible state.
So, I approached the third example with a fair degree of scepticism. A 1979 model for £1200, claimed to be in good running order with 19700 miles done. It looked okay, ran after a fashion, which included the noisiest exhaust I had every come across, and was still as bright red and white as it'd come out of the factory. A test ride, a lot of haggling and it was mine for 700 sovs.
Although the Desmo is very rare its specification is nothing very special. A 497cc vertical twin with 180 degree spaced crankshaft, putting out a very modest 40hp at 8000 revs. Despite the paucity of power I was to find that it had a very narrow, 7000 to 8500rpm, power band and little by way of the usual vertical twin torque at lower revs.
This made it quite a thrilling bike to ride, like a two stroke it was an all or nothing kind of engine. It would not pull top gear all that well at low speeds, needing a change down to fourth or even third to put the motor back into its power band. The power would be searing, exhilarating until it hit 8500rpm when it would stop stone dead. I put 110mph on the clock on the first ride home and never bettered it thereafter.
Another clue to the nature of the engine was vibration. Beyond 7000rpm it smooths out to an acceptable level, below it was worse than many a British 500, the buzzing accentuated by the off beat exhaust and an engine that did not run cleanly below 3000rpm (probably down to the matt black cum rust silencers which did not appear to have any baffles left).
Part of this vibration was undoubtedly down to the fact that the neat chunk of engine alloy was a stressed part of the frame, the neat tubular trellis dispensing with any tubes underneath the engine. The chassis was certainly rigid, in more ways than one — the suspension was typically Italian in its tautness despite being the still original Paioli forks and twin shocks. I hate to think what they were like when new. As it was, they only seemed to move when thumped by a large bump at 70mph or more. All minor road irregularities were fed directly into the rider's arms and backside. At least I always knew what the Michelin tyres were doing (they did not seem to wear at all).
Handling was par for the course. The faster the machine went the better it felt. At low speeds rather a lot of effort was needed to set the bike up for a bend, but once convinced that it was a good idea to lean over rather than run off the road, it stayed on line with the precision for which all decent Italian iron is renown. The higher the speeds the easier it was to steer the bike and the more precise did the steering become.
These various factors all add up to the need to do 80 to 100mph everywhere. Unfortunately, the seven year old OHC engine did not quite agree with this philosophy. I was having the time of my life riding around on the Duke, really enjoying the buzz from screwing the motor along at its maximum revs, when after 750 miles there was this deafening cacophony from the cylinder head.
This was bad news. The engine employs the desmo system of opening and closing the valves using a pair of carefully matched rockers and cams on each valve. This system was originally designed to deal with the large valves in their singles and then was later incorporated into their V-twins. It's a wonderful piece of engineering which stops valve float at high revs but does require an expert to set up.
Armed with my big hammer and set of spanners I set to work. The engine came out with ridiculous ease, helped by the fact that you could undo the bolts and then pull the chassis away from it... when the attractive lump would topple over on to your foot. This put me in such a foul mood than when the cylinder head bolts refused to come undone I whacked the lovely alloy casting a few times with the big hammer.
Tough bugger, didn’t crack up or anything. Out with the penetrating oil, leave to soak for an hour (spent penetrating the wife, she wasn't amused by the grease marks) and hey presto - two bloody studs sheered off! It didn’t matter, the one piston had shattered after a valve fell out, so I had to take the cylinder off anyway.
The local Ducati specialist told me not to worry, he'd get the parts within the week. Three months later I was armed with pistons, rings, studs, valves, rockers and various gaskets. I handed these and the engine over to a local mechanic who claimed to know a lot about Ducatis - he had blinded me with enough techno-babble to last for a lifetime.
Three weeks later my engine was ready. Once installed, this time without injuring my foot, I was not too impressed. There were an awful lot of rattles coming from the cylinder head area and large clouds of smoke, as well as a lot of banging out of what was left of the silencers. I gingerly rode down to the local dealer who diagnosed badly adjusted exhaust valves. After pushing the bike around to the mechanic, he reckoned there wasn't anything wrong and I should just run it in.
Back at the dealers, they agreed to give the bike a thorough going over, but only for a hundred notes minimum. They reckoned the valves were stuck permanently open because the shimming was cocked up and demanded another £75 to fix it. I paid up, cursing under my breath. I reckon I was lucky not to have burnt out the new valves. The total cost including labour and parts had climbed to an absurd 600 notes, and I reckoned I'd done all the hard work myself!
After 500 miles of running in, I tried to rein in the right hand. It was jolly hard work as riding around in the lower rev range caused the vibes to blitz various fittings, the chassis responded badly to my inputs and the riding position, with pseudo clip-ons, played havoc with my arm and back muscles. Fuel consumption was also atrocious, about 35mpg compared to 40mpg when ridden in the glorious power band.
The Brembo brakes, an utterly absurd excess of discs, did not like the wet, when they lagged and suddenly came on all powerful. In the dry they were okay, very strong with a useful degree of feedback, but, as with everything else, were better at speed than town idling when they tended to pack too much of a punch. Front pad life was frightening - 3000 to 4000 miles. The rear disc was weak, refused to work in the wet and was usually ignored.
The machine kept getting the better of me, exhorting me to rev her to the limit all the time. Fantastic fun. After 6250 miles, though, I began to detect signs of top end rattle and the power punch started to tail off. I could not face yet another hugely expensive rebuild, so the machine was put up for sale.
The bike had been professionally resprayed in the past by the previous owner, so general finish had stayed excellent. The engine alloy could be persuaded to shine up beautifully with a bit of polish and hard work. The exhaust system required weekly doses of heat resistant paint, but it was probably original, which would have seen off most exhausts by then
These attributes convinced me that I could flog it off as a pristine classic. It took four months of expensive advertising to sell for £1250. I certainly didn't make a profit, but I suppose I could have lost a whole lot more. The bike was useless in any other mode than flat out riding, when its engine reliability suffered traumatically. I wouldn’t buy another because I like to ride my bikes rather than have to muck around with them all the time
F. H. K.