Easy fix is the gasket is bad and you need to replace it. Best done by two people. There are about 7 screws up there.
Open the winddshield, place a blanket on the gas tank, have someone hold the frame, take the screws out. Set the windhield aside and dry fit the new gasket. Reverse the procedure.
There will pros and cons about putting some kind of sealer in there with the new gasket.