Might need to clean the pilot jets.. I've seen the same reaction on some of the new bikes after they have been too long in the crate. I take the carbs apart for a thorough cleaning but you might get lucky with some kind of cleaner.
You might try draining the fuel bowls then spraying an ample amount of carb cleaner into your fuel line. You might get lucky, just make sure it's outside when you start it though.. that stuff is pretty toxic when it burns. Cleans the combustion chamber too.. I wouldn't advise it on a regular basis but once ain't gonna hurt.
