Maybe the previous owner removed the tank for some type of maintenance before putting the bike up for sale. If so, he might have pinched the breather tube underneath during reinstallation. Loosen the gascap and see if the problem persists. You also need to check the "hidden" fuel filter (see tech vault).

Jack

'08 America Blue/White; Custom Headlamps, Custom Lowers, Clearview 20", Bafflectomy