OT's Redneck Repair Guide vol. 1: Repair your leaky vaccum petcock for under $10.00
If you've lived in a dry climate (say, Arizona) or you've had your Harley for a while, chances are your petcock has leaked fuel at one time or another. Now if you're like me and own a late model Harley, you've probably got a vaccum actuated petcock on your bike. These can be fairly expensive to replace. Even a gravity petcock can run you $30.00 or more by the time you figure in new fuel line. However, just because your vaccum petcock has a rotten diapharm and leaks doesn't mean that you have to spend a bunch of money. Now unfortunately HD doesn't sell a rebuild kit for these because they'd rather charge $92.00 for a new one. So what can you do? Fabricate your own rebuild kit.
Vaccum Petcocks 101: (Feel free to skip this if you want to)
As you disassemble your vaccum petcock you'll notice there are two independant cavities seperated by a rubber diaphram. One of these cavites contains a spring attached to the diaphram and the chamber is connected to the bike's vaccum hose. The other cavity is where the fuel flows through the petcock. There is a plunger attached to the diaphram on this side. This way when the engine is not running, the spring on the opposite side of the diaphram presses the plunger into the fuel cavity and shuts off the gas. That said, it is typically this diaphram that gets dry rotted in hot arid climates and begins leaking fuel. Though a vaccum actuated petcock is a nice idea. It's extra bullshit. You don't need it. For years bikes only came with gravity fed petcocks.
What does this mean? We're going to convert your fancy schmancy vaccum petcock into a proven old school gravity feed. Here's how.
Tools you will need: Phillips screwdriver, pair of pliers, 3/4" hose clamps (2), any type of rubber material that will make a good seal and can withstand gas and some heat, and a pocket knife.
Step One: Remove the fuel and vaccum lines from the petcock and drain the gas tank. Once this is done, remove the petcock from the tank.
Step Two: On the back side of the petcock there are four screws. Remove them and the two back plates, then remove the actuator spring in the vaccum chamber
Step Three: Lay the petcock, backside down, on your chosen piece of gasket material and trace the outline of the petcock with your pocket knife. You now have a new form fit gasket for your petcock.
Step Four: Prep the gasket for reassembally by punching four pilot holes to allow for the screws you removed earlier.
Step Five: Place gasket in front of the diaphram plunger (or directly over the fuel cavity), replace the two back plates, diaphram and all, but leave out the actuator spring. Replace the screws and tighten the living hell out of it!
Step Six: Re-attach petcock and reconnect hoses (since you destroyed the factory hose clamps, now would be a good time to use a new one).
Final Step: Re-fuel bike and run it for a while. Kill the engine and check for leaks. If there are none, congratulations, you're done. Just don't forget that now you'll have to shut the fuel off manually using the petcock valve.
"I've watched way too many episodes of junkyard wars!"
Americans play to win at all times. I wouldn't give a hoot and hell for a man who lost and laughed. That's why Americans have never lost nor ever lose a war. -- Gen George S. Patton
Last edited by OscarTango; 06-13-2003 at 09:36 AM.