Since you say clean the carbs, I am hoping you set the idle screws and also balanced the carbs after the cleaning. If not I would do that also. Yes it could be a float level off but if that was the case I wouldnt think the cylinder would fire with the enrichment activated as I believe it gets the fuel from the float bowl. When you rev up the engine, does it seem to be firing then on all 4 cylinders? You could also pull off the air cleaner lid and observe the 4 plungers and see if they are all moving at idle or at a slight rev up. The bike wont run proper above 3K rpm with the lid off so it wont work to leave it off to ride it.
Good luck and lets us know how it goes..