Petcock markings....what?

This will sound stupid I know, but i just took a good look at my tank's petcock for the first time and I'm a bit confused by the markings. To the front is marked RES, down is marked PRI, and to the rear is marked ON.

So...where should it be when I park it for a long time, and where should it be to run? And finally, what is PRI? Had a guy tell me to move it back (to ON) when parking it, but that doesn't make sense to me. Anyone know these markings?

RES = reserve
PRI = prime

You have a vacuum operated petcock that relies on the engine vac to open a diaphram in there which in turn allows the gas to flow.

The default setting is ON. While ON the gas will not flow unless the engine is running. ON position draws gas from slightly higher up in the tank than RES.
RES is your reserve setting that will also no flow gas unless the engine is running. You flick the petcock to reserve when your bike strarts to sputter in the ON position, the you get yer butt to a fuel station quick!

PRI is the prime position that will provide unrestricted fuel flow no matter if te engine is running or not.

You can disconnect your lines without fear of gas flow in either the ON or RES position.

Cheers!

It's a vacuum style petcock, meaning it uses engine vacuum to actuate the valve.

So the guy that told you to turn it to "ON" while parked was correct. While in the "ON" or "RES" position the valve will be closed until engine vacuum is present. "PRI" or prime as TerryK mentioned, bypasses the vacuum and opens the valve to get fuel to the carbs if they are empty for some reason.

Hope this helps

How long dows it take the PRI position to fill the carbs if the bikes been parked till dry?

polkat wrote:

How long dows it take the PRI position to fill the carbs if the bikes been parked till dry?

about 10 seconds

Yeah, very quickly.

You really dont need to use prime ever unless you are installing the tank after some work/maintenence or something.

A related "trick" here is what is "ON" and what is "RES" in relation to the position of the lever. My owner's manual is incorrect (1982 1000J2). The "arrow" on my handle points to the appropriate position.

Who was it that decided to call a selector valve a petcock.Ive always had a problem calling anything a petcock.

Now that I think about it I think about a petcock was used to tap a keg they would put it in the Bung Hole and have a drink.I kinda like the fact that I have a vacuum actuated one