I got my first proper bike just on 42 years ago - a Kawasaki KH250 3 cylinder two stroke - I was hooked. I loved it, went everywhere on it including my first ever proper holiday without my parents - a 2 week break in the Isle of Wight. Of course it didn't take long for a fault to rear it's ugly head - the plug in the middle cylinder decided it also wanted a holiday. It did it quite often and stupid Dave had forgotten to put a spare plug in the holder that Kawasaki had rather thoughtfully provided under the seat. There weren't many bike shops on the island - the yellow pages suggested one quite a few miles away in Carrisbrooke. Me and my mate went there and discovered the place shut. I decided there and then that if I was to get another motorcycle I would get a reliable four stroke - loads of my mates had Honda dreams and super dreams and I don't recall any of them ever breaking down.
Just recently I have been enticed back to two strokes and have developed an unhealthy interest in Aprilia rs125's in particular. I love the madness of a 35bhp 125 that weighs as much as a packet of crisps - one of the multipack ones, not the full bags you buy individually. These nutter machines will easily hit the ton in unrestricted form and the sheer joy when the power valve opens and the ful power is unleashed is quite remarkable. Once again though - they are very unreliable and eat pistons and rings with boring regularity.
Anyway where this is going is that while I have always admired the mad Italian styling of recentish Ducatis I have always steered away from them and their quirky desmodromic valve gear. That is until this week when I got offered a project one at a price that I couldn't ignore. There was a reason for the low price, which I will get in to but first a bit of info on these desmodromic valves.
In yer average 4 stroke engine you have valves that are opened either directly by a cam or via some sort of push rod or rocker arrangement. It's all quite simple, just about every 4 stroke uses the same system - the valves are slammed shut by pretty heavy duty springs - on bikes and high revving car engines there is often 2 springs per valve, it helps stop the valves bouncing at very high revs. With bike engines often hitting 14,000 RPM that's kind of important. A closing valve will slam in to the head at very high velocity, if it open again even very slightly when it's not supposed to it really messes up power and economy. In extreme circumstances it can result in piston to valve contact, although I have never seen this happen myself even on highly strung race engines. The desmodromic system has two rocker arms for each valve - one opens the valve and the other closes it. In theory this allows for a much higher revving engine while the load on the valve gear is reduced by not having really hefty springs to be compressed thousands of times every minute. for me, the biggest disadvantage is that they can be a pig to set up and engine damage can occur if it is done incorrectly.
Another thing that put me off was the fact they have rubber cam belts whereas just about every bike I deal with these days is chain, the only exception being the honda Gl1100 goldwing engine in my trike. They need replacing every few years, they are not cheap and they are a bit of a faf to do on the dukes - yppu need a special tool just to turn the crank.
In a strange and perverse way as I have got older the mechanical marvel aspect of these things has got more and more appealing so when this one came up cheap I had to give it some consideration. I nearly walked away when I discovered it was cheap because the previous owner lost the keys. That's a seriously sub-optimal scenario on these bikes as you then have to get the immobiliser reprogrammed and new chips to match in the red master key. Once you have the red key matched you can program additional keys at will but getting there is very expensive and not many specialists exist that can do the job.
The bike is very low miles for it's age, it is also in well above average condition. I think it's worth saving, it should arrive tomorrow and first job will be to remove the instrument cluster , which contains the immobiliser and get it sent off with the keys for re-education. This is obviously a huge gamble as I can't hear it running with the immobiliser interfering in things, it's coming from a dealer I trust though so it should be ok.
it's definitely a marmite bike, I think they look mega from the side and rear but hate them from the front. Everybody that has reviewed them says they are superb to ride, I don't know as I have never ridden one. I'll let you know when it's up and running.
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