And don't leave gas in the generator when it isn't being used for a long time. There's a drain plug on the carb for a reason. It used to be you could buy a rebuild kit for the carbs, but anymore they only sell new carbs that are expensive and not commonly stocked.

I've had good luck with Sta-bil in the tank, but I always drain the carb or shut off the fuel and let it burn the remaining fuel off.