How do I know what size petcock I need for my motorcycle?

The first consideration when choosing a petcock is to determine which direction the petcock outlet needs to be facing, left side, right side, or vertical. Next you need to know two measurements in order to choose the right petcock for your motorcycle. You need to know the size of the fuel inlet on your carburetor. Typically, you want the same size fuel line going from your petcock to your carburetor. The second measurement is the thread pitch and size for your petcock bung on your gas tanks. Your petcock has to have the same thread pitch and size in order to mount into your gas tank.

How do you know when your petcock on a motorcycle is bad?

Typically, when your petcock goes bad one of a few things can happen. If the petcock has a diaphragm inside, and it goes bad, the petcock will leak externally. If the seals go bad inside the petcock, it will allow fuel to pass when the valve is closed and in some cases will slowly siphon the gas out of your tank. If the petcock fails due to debris or corrosion, it will simply not allow gas to flow.

Is it okay to use a cheap petcock?

A petcock is a simple valve. It allows gas to flow and it stops gas from flowing. Since the product is so simple there is really not a lot that can go wrong. A good metal petcock should give you many years of service. Just buy something decent so you don't get stranded on the side of the road.

What is Reserve on a petcock, and how do you use it?

The reserve setting on your petcock allows you to draw fuel from the bottom of your gas tank. During normal operation of your motorcycle, you should set your petcock to the “on” position. This will allow fuel to flow from the tank through the top portion of the petcock and out to your fuel system. When you move the petcock selector to the “reserve” position, it allows the fuel to flow from the tank through the bottom portion of the petcock and out to your fuel system. This reserve function allows you to get to the next fuel stop before you run out of gas.

3/8 NPT Motorcycle Petcocks for Harley, Sportster, Chopper, Bobber and more