With the lever down, you are in the on position, lever up reserve and lever either forward or pointed to the rear is off .
Don't know how long you have owned the bike, but one LS that I got, wouldn't shut off in the off position, the rubber washer inside had worn to the point of allowing fuel to flow .
May want to check this on occasion .
Where does the fuel line attach to your fuel tap, at the 6 o'clock, or 3 o'clock position ?
If it goes on at the 6 o'clock position, there is a small fine mesh plastic filter screwed into the nut that threads onto the fuel tap body, check it occasionally for blockage .