LM2 right cylinder running very rich

[Stevex]

Since riding the Le Mans after winter storage the right cylinder has been running very rich. Symptoms were occasional missing and back firing. Pulling both plugs showed the left side normal and the right one black but dry. I pulled the right carb apart, choke is free and bottoming, needle has no wear, floats are not leaking and float height is 18mm. Needle valve is working and looks good. I removed the atomiser and it looks ok, no obvious ovaling. Last year the right side occasionally chucked out some black puffs according to the wife, following on her bike, but it didnt miss or back fire.
Any advice please, I dont want to start chucking new carb parts at it without an idea Im heading in the right direction.
How much atomiser wear would cause the carb to run rich, with no obvious ovalling?

[Frenchfrog]

Couldn't say but whats the mileage ?  Personally a  new set of atomisers and needles ( they wear too !) would not be unreasonable for any bike over twenty years old and yours might be the originals?
Then there is valve guide wear perhaps...
A suggestion would be to swap the atomisers over and see what happens with new plugs?

[JoeW]

The choke plungers get hard and worn. Just because it's bottoming doesn't mean it is sealing. Usually, a leaky choke acts up more at idle than at speed.

[guzzisteve]

If you have aluminum needles, they wear faster than the atomizer. Check idle mix is correct. If you pull 1 plug wire off the cylinders should fire same amount of times at idle.

[wirespokes]

Keeping with the adage that 90% of carb issues are electrical, what plugs are you running? Perhaps a weak spark on the right side? Poor connections to the right coil?

If it was running fine when parked, poor electrical connection makes more sense to me.

[Stevex]

Firstly, I replaced the spark plug, hoping it would prove to be an easy fix...nope.
Next I swopped the float needle and seat hoping this was the cause due to over filling the float bowl, but no.
Next I swopped over the atomiser and needle, again, no change.
Having checked the mixture screw and its setting, I decided to swop over the choke pistons.
An improvement on the right side that was fouling the plug, instead of being fully black, only the inlet side was black and the exhaust side of the plug was brown. Expecting the left plug now to be black I was surprised to find it brown as before.
Im going to order new choke pistons for both sides and hopefully that'll sort it.
Got to love these Dell Ortos, so accessible and easy to work on. Ive had them off and on 3 times today, swopping bits over, and all done, including runs in 2-3 hours.
Thanks for all the advice, it never occurred to me to swop parts between carbs to eliminate the various parts and Im not a fan of diving in a replacing parts unless I can prove theyre faulty.

[Frenchfrog]

Sounds like you have it pinned Steve....
If you  can extract the rubber plus without destroying them they can be flipped over and as long as they are not too far gone will work perfectly after that

[nc43bsa]

I usually swap the carbs, side to side, to zero in on the problem.

[Stevex]

Ah, wish I'd read about flipping the rubber parts of the choke pistons before ordering new ones, never mind, they are cheap.
Bsa, flipping the carbs wouldnt have helped me. I knew the right carb was the problem, I just needed to work out which part of it was the cause.

[Frenchfrog]

Yeah sorry Stevex...my mind is not as fast as it was 

[huub]

aliexpress has the choke plungers stupidly cheap ,
i have a few new ones in stock , every old guzzi i work on gets new ones as a precaution