I did the valves

[Chris & Nean]

My bike was running rougher and rougher as the miles toted up! I had done about 14000 (I lost count exactly how much due to having three sets of clock’s, fitted) I put Iridium plugs in and noticed a marked improvement in slow running. I was surprised new plugs would make such a difference and thought I was imagining it.

After having done the valve clearances I’m even more surprised, the bikes smooth right down to 2500 revs now, it still judders if I ask too much from it at such low engine speeds, but the on-off throttle response is much smoother.

I had 0.2mm on the exhaust closer on the vertical cylinder (it should be .05mm) and .05mm on the inlet opener shim and had to have new shims -that needed sanding down a bit. But the bike ran so much better after adjustment I can see now why valve clearances are so important. I had the heads off to do the job, and I think this is the best way if doing the valves for the first time; I was able to sit at the kitchen table fiddling with the head and valves and pulleys until I had a good feel for how the Desmo system worked. I would have struggled had the heads been on the bike with belts still in place; you literally need tweezers for the little spring retainers, it must be a pain getting them fixed in on the exhaust valve tucked up behind the rear suspension spring and its leavers.

I made a tool for undoing the head nuts, it’s an old 14mm King **** ringer fixed to a half inch adapter off a worn out impact driver I had. I heated the adapter up to red heat to anneal it, to be able to drill it for the sawn off shank of the ring spanner.

[gremlin]

valve clearances close up on bikes, the valves bash into the cylinder head seats and "mushroom", which causes them over time to effectivly be further into the head, hence the gap closes up. the valve heads need to seat correctly for 2 reasons. 1 is to seal and give good compression, but the second is just as (if not more ) important, and that is , when the valve head touches the head, it looses heat rapidly so it keeps cool.(even at 12k revs, it touches for enough time ) if it doesnt touch, the valve over heats and over a period of time will burn its edges thus making the whole problem even worse. what also happens, is that once the engine stops, the residual heat floating around will disipate throught the valve stems, which will cause the stem to expand and grow in length. so when you try to start the bike again when the engine is still hot, you will have far less compression than when the engines cold so it will be a pig to start. i would say that 95% of customers bikes we fix that have starting with hot issues , all have incorrect valve clearences, most garages will re-jet the carbs or re-map the ecu to mask this problem thinking its a fuelling issue, its obviously running too rich..........:fou::fou:

[jerry]

Yeah its amazing how well Ducatis run at low revs with nicely set up valves ,the pickup and responsivness ios better too.

[Chris & Nean]

I checked a buddies valves on his Multi 620 today, he had spec clearance's on the inlet on the horizontal cylinder, and 3 thou on the opener and 1 thou on the closer on the exhaust valve, couldnt check the vertical head though because the petrol tanks almost flush on top of it, how do they check the clearances on these things? the tank goes from right at the front to the back of the bike, it looks like a majore job just removing it to gain access.

[Dookbob]

it,s not really a major job, but a pain in the bum never-the-less, that was one of the reasons that I sold my 1000 multi, that and other crap design features. If you do any riding on the continent and have the misfortune to use petrol containing a percentage of that organic stuff, that can cause distortion of the tank too.