sorry to dwell on it, but what are the symptoms of bad vent? lack of fuel - stall? And is this vent in the cap or is it a tube that attaches to the tank?
Yes fuel starvation is the symptom. It's located in the side of the tank and is replaceable without having to swap the entire tank if you wanted to swap it for the heck of it. You have to separate the tank from the crankcase slightly in order to access it.