You'll need further complete disassembly of carbs down to every last nut, bolt and individual component for scrubbing with brushes and poking out with matching-gauge soft copper wires. Bike ran perfectly fine when leaving showroom floor. It will again when carbs are restored to factory-fresh clean with all factory settings.
Spray carb-cleaners no longer work due to removal of chlorinated compounds. Scrub with PEA-based fuel-system cleaners:
- Red Line SI-1
- Techron Concentrate Plus
- 3M Max Strength Fuel System Cleaner #08814
- Royal Purple Max Atomizer 18000
- Gumout All-in-One (may be off list soon due to reducing amounts of PEA)
Scrub-brushes from Amazon:
https://www.amazon.com/dp/B01N6QEINN
Scrub secret hidden passages in carb-body with PEA-based fuel-system cleaner.
N4MWD's blog: Secret Ninja 250 Carburetor Passages
Completely disassemble emulsion-tube and pilot jet. Poke out all lateral bleed holes with soft copper wire. Dried petrol turns to plastic and cannot be dissolved again. Must be mechanically scrubbed away. Also poke out all bleed-holes in carb-venturi towards float-bowl. Especially the mixture-screw hole.
Ultrasonic soak everything, micro soda-blast. Replace all rubbers: fuel-rail O-rings, float-valves, flow-bowl seals, pilot-screw O-rings. Set float-height with wet-test. Sync-carbs
That's a lot of work and requires lots of experience and equipment. Unless you want to practice and destroy hundreds of carbs to learn this kind of work, I recommend sending petcock & carbs off to ducatiman (gordon) for complete restoration work.
https://customcarbservices.com
Expert work, reasonable costs and fast turnaround! Bike will run like brand-new off showroom floor!!!
BTW - can search "ducatiman clean carbs" on this forum for procedure & photos of what's involved in thorough carb restoration back to factory-fresh OEM clean.