With my CBR carbs, there are two areas that get gummed up. The piston/needle and walls, and the idle jet. Spraying carb cleaner in the mouth of the carb may clean 1/4 of the piston. To do it right, and get the same snap as fuel injected bikes, the carbs have to come out for cleaning and adjustment. And like most carbs, taking off and installing them is 3/4 of the job.