We thank you for purchasing a manual petcock conversion kit from Murphs! The first step is removing the gas tank from the bike. We suggest running the tank down to reserve before removal, both for the ease of moving it with less weight, as well as positioning the tank during the petcock changeover. We will assume you have removed the tank before, but in case you haven t: Remove the seat Remove the two bolts securing the tank to the frame at the rear of the tank Place a rag on the plastics and engine under the petcock to catch any drips Disconnect any and all vent lines at the rear of the tank, and note where they attach for later Unplug the fuel gauge connector coming out under the rear of the tank Lift the rear slightly, disconnect the vent line from the under the right side of the tank Making sure the petcock is not in the Prime position, remove the fuel and vacuum lines from it Remove the tank from the bike, paying attention that the rubber bumpers on the frame stay in place Move the tank to your workbench. You re going to want to have the tank laying on its right side, with the petcock in front of you. To protect the tank, we recommend a layer of bubble wrap or similar on the bench, with a rag over the top. To keep the tank steady, roll up another rag and tuck it under the far side of the tank. If your tank is low enough on fuel at this point, there should be no fuel leaking out anywhere.
Remove the petcock from the tank. Two bolts secure it in place; you can use either a large Phillips screwdriver, or a 10mm socket. We recommend the socket. Now you can begin the actual conversion of the petcock. Start by removing the 4 screws that hold the vacuum diaphragm to the main body of the petcock. You will use the plastic block and diaphragm assembly in the conversion, so take care when separating the pieces. In particular, the diaphragm should be handled fairly gently. If it sticks to the metal pieces, and it likely will, use your fingers to gently work it off. You don t want to damage this piece, as it is not a replaceable piece by itself. Note, in the picture on the following page, the plastic block has been removed from the middle of the 2 diaphragm pieces. It is not necessary to do this.
Also note that when you separate the diaphragm from the vacuum block, there are little alignment nubs on the block, and the new piece as well, that match the holes in the diaphragm. These are spaced so you cannot put the pieces back together wrong as long as you are paying attention to the alignment.
Now let s move to the fuel valve side of the petcock. Remove the 2 screws holding the ring.
After removing the ring with the position labels, remove the lever. It may take a little wiggling back and forth to get it to come out. At this point you ll notice the o-ring, and just above that the wave washer. You ll be replacing the o- ring with a new one provided in the kit, and you will be reusing the wave washer. Work it off over the lever.
Now that you have all the parts off that are necessary for the conversion, this is a good time to do any cleanup on the remaining pieces. If there is some grit or grime under the valve handle, for instance, take the time to clean that up now. When you are satisfied, you can begin reassembly with the new pieces. You can do it in any order you choose, but for the purpose of these instructions, let s start with the vacuum side. Remove the o-ring from the end of the vacuum seal, and install the new one. You may want to use a bit of silicone grease (NOT sealant), or a drop of oil on the o-ring to ease installation.
Now we can install the new vacuum-side block to the main body. Be sure to line up the nubs that were mentioned earlier while you assemble the pieces. You ll note the recessed areas on the new block, as shown.
Back the set screw out, as shown in the above picture, during the assembly process. After you have this part put together, you ll turn the screw in until you feel resistance. Turn it just about 1/8 turn further, and no more. You don t want to deform the o-ring by over tightening the screw. Use a small wrench to snug up the lock nut against the base. Moving to the fuel lever, roll the new o-ring provided onto the new lever. Once again, you may want to use some silicone grease or a little oil to make it easier.
Work it into the valve body, taking care to make sure not to bind or roll the o-ring in any way. After that is complete, slip the wave washer over the new lever and into place.
Put the new sealing ring with labels over the valve handle, and reinstall the screws. The finished piece should look like this. At this point, you make take a look at the original valve body and think you should have spent more time cleaning it up, like this guy did! The last piece to assemble onto the petcock is the o-ring for the petcock to tank seal. While it may appear at first look the o-ring will not work, you will find it quickly forms to the shape of the groove in the petcock, and fits perfectly. Here again, use some silicone grease or oil. In particular, using the grease here will help to keep the o-ring in the groove while you install the petcock on to the tank.
All finished, it should look a lot like what is shown in the picture below. And all your old parts are left to save in the event you should ever want to reverse the process.
A good looking finished product, if we do say so ourselves! All that s left is to install it on to the tank, and put the tank back on the bike. In doing so, use the 2 new nylon washers for the screws that mount the petcock to the tank. Take a moment and clean up the area of the tank where the petcock is mounted. Tighten the screws evenly, and snug them up without overdoing it. At this point it may be a good idea to position the tank upright on your workbench, and run the valve through it positions to check for leaks. Of course, you ll want some kind of container at the fuel outlet to catch the gas that comes out. You likely won t have any, but if you do you ll likely need to check the screw on the vacuum side for snugness, as well as the valve handle/o-ring assembly. The last thing in the kit is the new vacuum cap. Remove the vacuum line that ran from the original petcock to the carburetor, usually number 2 carb. In any case, remove this line at the carb, and set it aside with your other original parts. Install the provided vacuum cap on the vacuum nipple. Mount the tank back on the bike, taking care to connect all the lines and electrical connection while doing so. Run the valve through the three positions, checking for leaks. Go for a ride. It is important to mention that this modification won t prevent fuel leaky carburetors from causing you problems with potential hydrolock situations. In order for this to work as intended, you must get in the habit of turning the valve to the OFF position when you park the bike. Put a flag on your keys, a sign on the dash, whatever works for you, but make sure to get in the habit of shutting the valve off.