when lever hangs down fuel is on (if selectors and bodies are correctly matched)
The operating circuit name ON, RES, OFF is under or covered by the lever handle ie. "ON" would be under(covered by) the lever handle when down. "RES" would be active and covered by the lever handle when it is up. "OFF" when the lever is cross-wise is (shown just over the lever handle.)
Of course, there are two versions of all this 1. for the left hand petcock and 2. for the right hand. The levered selector has a small "L'" or "R" which needs be properly matched to the petcock body for left or right side btw.
left hand petcock....long tube for on, is into tank on the left side of the two tubes and fuel exits from the rear towards the rear (right) of the bike. right hand petcock....long tube into the tank is on the right side and fuels exits towards the rear (left) of the bike. I'd take pics but wife has my camera today.