Should the Petcock be in the ON OFF or Reserve position when refuelling?

Makes no difference! Just ensure it is back in the on position not the reserve position after it is filled Remember on some bikes its not an off position either. Most new bikes use a vacuum system to turn on and off the fuel and the off is actually the on. Or always on , vacuum on and vacuum reserve on.

== If you have a gravity-fed fuel system, you should turn it off whenever the engine is not in use or gasoline will invade your oil and cause problems.