A closer look at the fuel petcock – Honda CX500, GL500, CX650, GL650

The petcock screws onto the underside of the fuel tank, and controls the fuel flow between the fuel tank and carburetors. It incorporates a fuel filter screen, which can be seen on the left side of the below image:

In the above image the petcock is set to “off”. A closeup of the fuel filter screen:

The screen consists of a fairly fine mesh, but rust and dirt particles can make their way through to lodge in the carburetors, so it is not 100% effective.

The brass coloured straw coming up out of the petcock body is what the fuel flows down through when it is in the “on” position – this way there is still fuel left in the tank beneath the top of the straw when the carbs run dry. Then, when you turn to the “reserve” setting, the fuel is drawn through at the level of the petcock body – you can see the C-shaped hole here around the base of the straw:

The filter screen sits over the whole lot:

Rubber seal at the base:

We will disassemble a petcock body and post back once that’s done.

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