TOPIC:

So i remove all three enrichening( piston and diaphrgam),the engine improve a lot when i start from standstill,now i use less the clutch.
As Scotch did,i also retarded the timing 5 degrees and the idle increase 100 -150 rpm.
Spark plugs fouling slight decrease and piston crown are less wet,and so far i didnt ^loose^ any cilinder.
I removed all 6 pilot idle jets, the holes are ok but outside there are marks from the screwdriver. I have to change them?
For the big diaphrgams:when i slight open the throttle they start to vibrate and a lot of petrol spray out from the needle.

Fabio
the holes are ok but outside there are marks from the screwdriver.
Sorry, I don't understand this. A photo would be very helpful

For the big diaphragms: when i slight open the throttle they start to vibrate and a lot of petrol spray out from the needle.
Typically, the only way fuel can come out of the main-jets is with high venturi vacuum (high air velocity) which requires the throttle to be substantially opened.
Float level(s) could be too high. Are you using the factory original Nitrophyl floats?

For myself back in the 80's I drilled a hole to fit a 1/8 pipe plug in to the front side of the alt cover on the right side of the crank and then loosened the timing screws a little and using an adjustable digital timing light set the timing that way, never had much faith in the timing mark method. Sorry for the brightness of the image bike is parked in a dark spot in the garage

[attachment=9791]

Scotch
I did a better checks and yes, the diaprhagms vibrate but only wnen the throttles is open.
The floats are the original one, the level is 7 mm under the edge
I drove it about 150 miles in urban roads with no issue,consuption is reduced and i didnt loose any cilinders,
as you can see in the pic,the spark plugs got different fouling aniway is very easy to clean them just with a rag

this is another scenario where we start shooting into the darkness and hope we hit something....metaphorically.
IF you believe other parameters are OK then try turning IN (leaner) the pilot screws 1/4 turn. If you used a "Color Tune" initially, don't bother with it for this adjustment. The Color Tune has a wide range and it easy to set the pilot screws on the rich end of the adjustment range.

Many timing lights have a dial in degree adjuster so you can tell the advance/retard from tdc mark.