How do I operate the petcocks on my motorcycle?
 

Hey. I have an 82 Yamaha with gravity fed petcocks (fuel valves) on both sides of the fuel tank. They are both different manufactures (one old, one new). I can't seem to figure out where to set the knob to reliably fuel the engine. There is no "on" setting, just "Off""Res" and "PR". I'm guessing PR stands for primary, meaning main fuel supply. But when I point the little arrow at PR, the engine wont start. With some fiddling I can get the engine going, but I have no idea If I am pulling fuel from the main tank or the reserves or what. Can someone tell me how to correctly operate these things?Thanks, JB

don't worry son. i had the same problem on my old triumph.. just unhook the fuel line and turn the knob.. if gas comes out its open

I reckon the only way to know is to pull the fuel lines off and turn the handle until fuel comes out. Then you will know what is what.PS. It would be wise to connect a separate piece of hose to the outlet and run it to a clear jar so you don't spill gas all over the place and create a safety hazard.