Have you tuned it up recently? its hard to tell if a bike is tuned on a nice day, only when it gets cold does it start to show. try changing the plugs, air filter, oil and filter, and put a little seafoam in the gas (about an eighth of a bottle to a tank- do this every fill up until the bottle is gone) also, drain your carbs and let them fill back up, there may be a little water in there from condensation.