I had this happen as well last week with my G5. i rode around on some errands, got home and filled the tank from a can in the shed, the gas i put in was cold, it was a cold morning, by the time i left for work it was running down the side of the tank. i figured it was just the fuel expanding as it heated up, am i correct here or is there another cause?
also brings up another question, and sorry if i'm hijacking the post, I like to figure my fuel economy, how do i fill a motorcycle tank to the same level everytime?