Harley Fuel Valve Install
The stock Harley fuel valve is simple, but once the sealing surfaces are worn, it can seep fuel even when the shutoff is tightened down. On my 1964 FLH Duo-Glide, I replaced the original valve with a Carl’s Cycle Supply PEEK-tip shutoff while keeping the stock-style Panhead tank layout. For more maintenance and workshop articles from the same project, see the Panhead Tech section.
Why Replace the Original Fuel Valve
The fuel valve on my 1964 Harley-Davidson Duo-Glide tends to leak a little now and then. It is not a major problem, but I decided it would be a good idea to fix it before it dumps a couple gallons of fuel on my garage floor.
The original valve uses a metal-tipped rod that is tightened down against the lower tank fitting to shut off the fuel. This tip has to be carefully lapped so it seals perfectly with the brass insert inside the lower tank fitting. Use and age slowly wear out the tip and brass insert until fuel can start seeping past the valve, even when it is tightened down.
If you are not interested in learning the fine art of fuel valve lapping, then I suggest you do what I did and call up Carl’s Cycle Supply. They have a new fuel valve that uses a tip made from PEEK. For those chemistry buffs, PEEK, which is short for polyether ether ketone, is a semicrystalline thermoplastic with excellent mechanical and chemical resistance properties that are retained to high temperatures. The bottom line is that this tip will seal better and last longer than the original without the need for periodic lapping. Besides the difference in tips, the two fuel valves are identical in construction. Every hole, thread, etc., matches up perfectly to the original.
Drain the Tanks First
The first step to installing the new fuel valve is to drain the fuel tanks. An easy way to do this, if you do not have a siphon, is to detach the fuel line down at the carburetor and add a length of rubber tubing to the end of the metal fuel line. Then you simply route the rubber tubing to a gas can and open the fuel valve. Make sure you pull the knob all the way up so that it is on reserve.
Once the fuel is drained, remove the crossover line where it connects to the right-side tank. At this point I went ahead and removed the tanks, but that is an optional step. If you do plan to remove the tanks, it is a good idea to loosen the lower tank fitting while the tank is attached, so you can get decent leverage on the fitting.
Disassembling the Original Valve
To disassemble your old fuel valve, first use a 1-inch socket or wrench to remove the lower tank fitting. Next unscrew the knob that operates the valve at the top of the tank.
My bike has an “accessory knob” which is not listed in the parts manual but is held onto the fuel rod via a short threaded stud. The factory setup just uses a single screw. Whatever setup you have, you first need to unscrew the accessory knob or single screw.
Once either of these is removed, you will be left with two knurled fittings. The top fitting is pressed onto the end of the fuel rod and should pop right off. The lower fitting is screwed into the tank and may need some careful persuading with a pair of pliers to loosen. With the lower knurled fitting out of the way, you can remove the spring, washer, and seal that are on the top end of the fuel rod.
Installing the New Fuel Valve
Once all the parts are removed from the top end of the fuel rod, it can be dropped out of the bottom of the tank through the hole left by the lower fuel fitting. To install the new fuel valve, just reverse the above steps.
Take note that if you have the accessory knob, there is a small length of threaded rod which screws into the end of the fuel rod that needs to be reused. Everything else will be replaced with the parts from Carl’s Cycle Supply, including all the necessary seals. As an added precaution, I used a dab of Loctite blue on the threaded rod. I hate to lose that knob on the road.
Comparing Old and New Parts
Before installing the new parts, I took a few minutes to compare the new and old fuel valve. My original fuel rod tip had plenty of wear as well as some pitting. No wonder I was getting the occasional leak.
Final Installation Tip
After everything is reassembled, close the fuel valve before tightening the lower tank fitting. This will ensure that the fuel rod is seated properly in the lower tank fitting. Also do not forget to reattach the crossover line to the right-side tank. My last step was adding a genuine Carl’s Cycle Supply sticker to my oil bag.
