Pilot screw loosening

[mh]

This is the third time in as many months that I've gotten around to adjusting my pilot screws and the front is way off again.  There's not much friction turning it even at the optimal position (5 turns out), so I'm assuming that the engine vibrations are causing it to back itself out.

So, how do I fix the pilot screw so it doesn't keep loosening?  Is there anything I can do without actually removing the carb?

I assume that the O-ring on the pilot screw is just very worn and needs to be replaced.  How do I remove the pilot screw so I can then get to the O-ring and replace it?  Is it as simple as completely backing the screw out? (if so, why hasn't my pilot screw already fallen out?)  What size is the O-ring?

TIA,
-mark

[Lucky]

Is the carb an 82 or an 83? they are vastly different. Here are the normal parts for an 82: pilot screw, spring, metal washer & o-ring. (assembly to the right below)
 assuming everything is there, you can just streach the spring very carefully and only slightly. ?we are talking only 1 or 2 mm here.

I have had luck matching up the 0-ring at a local, very well stocked, hardware store.

if the carb is an 83 then you have an adjustment screw that acts on a ball bearing that actually pushes on the pilot screw, see below for a pic of all the parts layed out in order. same thing here though, very slightly streach the spring on the adjuster (not the one on the needle) out.


"streach" doesn't look like i spelled it right... hmmm...

--Lucky

[mh]

Thanks, Lucky- I got to fixing my bike last night before leaving work and your instructions made it a ten minute job.  I just had a little problem pulling the pilot screw out after I had fully loosened it, but somehow I managed to grab the sides of it without resorting to going back into the building to get some tweezers.

Interestingly, the O-ring had wound its way halfway up the spring because there was no washer.  I hope its absence isn't too detrimental, I wouldn't know where to start looking for such a small washer.

The spring is really stiff- I used my screwdriver to pry apart a couple of the spring windings.  Then I put the spring over the pilot screw and the O-ring on after that and put the thing back together.  There was much more friction on the screw, which is exactly what I wanted.  I'll have to see in a month if things have loosened up or not.

Thanks again,
-mark