I don't think you want to run carb cleaner. If you're gummed up it won't help. In any case it would be too little too late. If you drained the fuel from the carb bowls I think you'll be fine. If not you may have a fully blocked jet, a partially blocked jet, or maybe nothing wrong at all. It becomes a little scary because a partially blocked main jet will almost certainly burn down your engine, but you may not notice anything is wrong until it's too late. If I didn't drain my carb bowls and hadn't touched the sleds for a year I would be inclined to start them all up and make sure they rev up and idle just like they did last year, then put in new main jets. But if you're a gambler they will probably be fine with some fresh gas in the tank.