A big issue concerning gas is that there's a lot of ethanol in it these days, and ethanol is hygroscopic, meaning it absorbs water from the atmosphere. During the prime riding months, it's no big deal. Most of us probably burn a few tanks a week so the water goes straight out the exhaust. In the winter, it's just the opposite; our bikes sit and the water settles in the tank and fuel system creating all kinds of mischief. The fuel also degrades over time, creating gum-like deposits in the carburetor and fuel nozzles, which can cause real maintenance issues. The simple solution is to drop a few ounces of gas preservative (I prefer Stabil, but Sea Foam is another good one) into that tank before each fill up.