You don't have it then. It happens when the bike is turned off, sometimes long after it's been running. I'd be having dinner or something, and I'd hear this high-pitched whistle coming from the attached garage. Probably related to temperature changes, changing the air pressure inside the tank.
Edit: Some guy
youtubed the sound coming out of his.
It was so much fun when I'd occasionally ride the 250 to work, it's pretty much the opposite end of the spectrum from the Bandit. You can split lanes like a mofo on a light bike like that. I really miss that little bike.