You've done maybe first 5% of carb-cleaning job. Sitting for 10-15yrs definitely means full tear-down and restoration job. Disassemble to every last bolt, nut, individual component.
Scrub out all passages where petrol flows starting from petcock and all hosts before carbs with PEA-based fuel-system cleaner. Carb spray cleaners no longer work due to removal of chlorinated compounds. Scrub hidden secret passages in carb-body with brushes.
https://n4mwd.blogspot.com/2013/10/s...-passages.html
Poke out lateral bleed holes in emulsion-tube and pilot-jet. Just because you can see light, doesn't mean it's
enough light. Bleed holes can still be constricted. You'll find poking out bleed holes with matching size soft copper wire will push out little dried petrol plastic plugs like little grains of sand. They can be translucent and transmit light, but completely block petrol flow. Also work from carb venturi side. Bend copper wire 90-degrees 5mm from end and use it to poke out bleed-holes in venturi. Those gets clogged too.
Then ultrasonic soak everything (except rubbers). Micro soda-blast everything. Reassemble with new rubbers. Sync carbs. That might be enough to restore to factory-fresh clean condition.
Otherwise, start from beginning and do it all over since you may have missed something. Many, many expert mechanics with decades of experience have had to remove their carbs 4-5x for ever deeper cleaning before their bike ran like new showroom condition. You might as well do full restoration to save yourself pulling 3-4 times more!
I've been working on bikes & cars for over 40-yrs. Can cut metal and build/weld frames from scratch; even casted my own engine-block once. And it still took me over 40-hrs to clean set of 250 carbs. Now I just send them to ducatiman to do for me because he's got all equipment needed and has tonnes more experience than anyone! Just do search on here for "clean carbs ducatiman".