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I have an older bike that has a 3 position petcock. I was trying to figure out which position to run it in as well as which position to store it in.

It is a 86 GPZ900r. The petcock has PRI, RES, ON. I know RES is for the reserve. Have been told the PRI is primary. Also been told the RES and PRI shut off the fuel flow when the bike is shut off, and ON will let the fuel flow running or not and flood out the carbs.

Thanks for your help

Pri = Prime - free flow of fuel, it jsut dumps gas into the carbs, good if your carbs have dried out, or you need to drain the tank. Bad to run on, as you'll flood them if you aren't using all of that up

On = On - standard run position, your bike will suck gas as it needs it

Res = Reserve - the backup part of the tank, typically 2 liters, or a 1/2 gallon. This is here so you have a chance to fill up after you "run the tank dry"

Off = Off - means the tank cannot dump fuel into the carbs. Just whatever is left in the fuel line.


Take the MSF course, they will explain all of this stuff, and teach you to ride safely.

I would say that you leave the petcock in the "ON" position to store or park your bike. Fuel will only flow when the motor is running in that position. When the bike starts that horrible stutter as it gets really thirsty, switch it over to "RES" and get to a gas station.

Thanks for the replys. I am taking the MSF course in the spring. You answered my questions!