I recently had success with a Sea Foam treatment. My bike had sat with fuel in the tank for who knows how long. I used more than recommended by the manufacturer, approximately 3 oz/gallon. I then went for a 5 minute ride and parked my bike for about 3 days due to rain.
The next time it was started, the rough idle and generally poor performance had greatly improved. It's not a substitute for a proper carb cleaning, but for $12 a can, it couldn't hurt to try.