I have had a similar problem with my bike when I first got it
and I pulled and cleaned the carbs 3 times and finally got it to work but it still wasn't perfect... so I decided to pull them and send them to Ducattiman
instead of trying to do it again... the internal passage ways are near impossible to clean without special tools....
I even bought a ultra sonic cleaner, but I don't have a soda blaster
so I just decided to let Gorden do the hard work for me rather than take a week to do it myself...and then perhaps have the same problem still
....mine work now but it takes forever to get off the choke it is very cold blooded when it's cold it will not take throttle at all.... so yes I believe it's the internal passage ways that are restricted
save the headaches and send them to Ducattiman !
....the price he charges is reasonable
...
Bob.....