Hello, firstly let me first say that I have no experience cleaning carburetors. Since the CBR had been sitting for five to six years without being used, the first thing I did when I got it was clean the carburetors. The bike wouldn't start after I cleaned them and correctly reattached the throttle cable. So I tried using starting fluid. It did start, but every time it starts, it goes to Full Throttle or dies. It only runs for a few seconds at low RPM before switching to Full Throttle. I made sure the throttle cable was connected properly.

 

Is butterfly valve on carbs fully closed?
Rubber manifolds between carb to head fully-seated and clamped?
Vacuum-measuring ports for syncing capped?

Well, you might as well pull carbs for deeper cleaning anyway. That's not sufficient cleaning for sitting 5-6 yrs. Bike ran perfectly fine when leaving showroom floor. It will again when carbs are restored to factory-fresh clean with all factory settings. Needs complete restoration by disassembling down to every last nut, bolt & individual component (different model, but all carbs are similar):



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:
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. I just send my carbs to this outfit for refurb every winter when I'm overhauling my race bike. Since I run in stock class, restoring carbs to factory-fresh condition is one of "mods" that make HUGE difference compared to others running with clogged carbs causing stumbling and revving laziness.

https://customcarbservices.com
Expert work, reasonable costs and fast turnaround! Bike will run like brand-new off showroom floor!!!