suzuki king quad 300

Hello, i have a 1997 suzuki king quad 300 and it runs well but when i shut it off and let it sit for a while the crankcase fills up with gas....i took the carb out and cleaned it and put a new float in it but it didnt help,...any help and suggestions will be greatly appreciated..thanks

petcock valve on suzuki king quad

on my 1997 suzuki king quad there is no selection on the petcock fuel valve to turn the gas off so does it just turn itself off when not running. i am thinking this why the gas flows right through my carb and into the crancase oil. would anyone agree that the petcock valve is supposed to shut off and it doesnt which is causing my pronblem