It was 84* yesterday and I noticed at red lights I could smell gas. Nothing leaking, but I believe that there is a vent on the K& N air cleaner. I also believe my mileage is down. Could something be wrong?

No vent on my K & N air filter.

There is an overflow hose from below the gas cap area that dumps out under the engine in case of spillage when fuelling the tank. Did you spill any gas the last time you filled the tank?
Did you fill the tank right up to the lip?
What year is your Swing?
What is the mileage?
Some Swings have evap canisters to contain fumes from the gas tank. More info is needed before any kind of diagnosis can realistically be offered.

2006 wing, there is a little nipple vent under the K&N filter, yes every once in a while I do spill when filling up, also 16K miles.

Spike,

You didn't eat a 'extra spicy Burrito" just before riding did you? That could explain the gas. I know that Gary (Opalsboy) did this once. Like Terry said (Bigbird), it may be overflow from gas when you filled up. If you find the problem, if there is one, please tell us.