I noticed the other day as i was riding my new to me 04GS500F that i left the petcock turned to what is supposed to be the off position but the engine was still getting gas. when i turn the petcock to on it continues to function normally but when i need to switch to the reserve that still functions. should i be concerned that i can't actually shut off the gas with the petcock or just leave it be since the bike is still running fine.
Your petcock has no off.It is vacuum operated.When you shut the bike off with it in the on position,the vacuum bleeds off slowly,closing a diaphram in the back of it,effectively shutting off the flow of fuel to the carbs.Use PRIme to fill the carbs before you start it.