Springtime is here and it is time to get the bike ready for the road again. If your bike is running a little rough after sitting through the winter months, it is possible that a basic carburetor cleaning will do the trick. A lot of people completely shy away from carburetor work, because it is typically considered more “complex.” This is true, especially when you get into situations of re-jetting, tuning, and synchronizing multiple carburetors.
However, there are some things you can do, and you shouldn’t hesitate to give them a shot. To give you a little context and back-story, I am currently doing a frame-on restoration of a 1972 Harley Davidson FLH Shovelhead. The bike ran, but ran very rough before I started pulling things apart. Now, this could have been for a myriad of reasons, including the carburetor being dirty, the head gasket leaking (air gap), etc. That said, I still decided that a basic carburetor cleaning was a good idea while things were disassembled.
Here are my basic pointers for carburetor cleaning, based on my recent experience. Keep in mind that I am working on an S&S Super E carburetor, but that a lot of the advice I provide is universal.
1) First and foremost, be gentle as you perform these steps. Unlike the rest of your motorcycle, the carburetor has a lot of small parts that can be easily damaged. This isn’t like working on the rest of the bike where a little elbow grease often helps. Get in the right mindset before getting started.
2) Set up a clean area to work. Scrub down your work surface and maybe lay out paper towels or other shop cloths directly below what you are working on. Think surgery. The carburetor is essentially the lungs of your bike and you want it to be as clean as possible when done. Also, this will help you find any small washers or pieces that might fall out unexpectedly.
3) Get a manual that covers your carburetor. For a factory carburetor, obviously look for a full shop manual. For an aftermarket carburetor, find literature from the manufacturer. It took me maybe 3 minutes to find this manual online for my carburetor and it helped a lot with the carburetor cleaning.
4) Remove the carburetor from the bike if you can (don’t forget to turn off the petcock and disconnect the fuel lines, first). This is easy on a Harley and more of a pain in the butt on a Japanese bike, but having the carburetor(s) off the bike gives you a lot more flexibility in terms of turning and flipping the carburetor around on your workbench for cleaning.
5) Get a new bowl gasket and air-cleaner O-ring. Technically, these can be reused, but why waste your time or risk it when they cost so little. Order them ahead of time, so you have them ready for carburetor cleaning day.
6) Drain the carburetor “bowl.” The bowl is the bottom part of the carburetor that generally has a drain plug at its lowest point.
7) Carefully, remove the screws holding the carburetor bowl in place. There are typically four to six of these and they aren’t always of the highest quality. Make sure you use a screw driver of proper size otherwise you risk stripping them. Given that these screws are of a very special shape and size, I would not want to have to replace these. Being careful and reusing the originals is preferable.
8) Once the screws are out, separate the bowl from the main body of the carburetor CAREFULLY. This goes back to point number one above. You can use a rubber mallet to tap around the bowl gently. This should break the seal between the bowl and body and allow you to easily separate the two. Don’t yank them apart!
9) The float sits inside the bowl and in the case of the S&S Super E is a black rubberized ring. You want to be very careful to clean above, around, and under the float without damaging it in any way. If you puncture the float, it won’t float the next time fuel enters the bowl and you will be in big trouble.
10) Remove the jets. The S&S Super E has a “brass-looking” main jet in the middle and a smaller pilot jet. These are both sticking out of the other side of the carburetor (opposite from the bowl). Again, these should be VERY CAREFULLY removed with the proper size screw driver or socket. Get a little Tupperware and soak the jets for a few minutes in a quality carburetor cleaner (use carburetor cleaner for the interior of the carburetor; you can use a regular degreaser on the exterior). Then get a can of compressed air and blow air through all the passages, making sure they are clear. Don’t stick things through the passages! These are precisely machined parts and nicks and scratches on their interior are not okay.
11) Clean everything else – inside and out with the carburetor cleaner and degreaser, respectively. Take your time and pride in your work. Keep telling yourself that your motorcycle breathes through this gizmo and it is important to do a good job. This will motivate you to keep at it longer than you might otherwise.
12) Reassemble the carburetor just as carefully reversing the steps above. This should be easy now that you took it apart, and you should feel a much greater sense of familiarity with the inner-workings of a carburetor if you haven’t been down this road before.
13) Refer to your manual regarding the idle screw settings. Generally, you will want to reset these after the carburetor cleaning, warm up the bike, and then adjust the idle speed and air-fuel mixture screws to get things running properly. This is going to be different from bike to bike, but the basic process is the same, essentially dialing in an appropriate idle speed once warm.
14) If you plan to store the carburetor for a while before putting it back on the bike and running it, I suggest putting the entire thing inside one of those jumbo 2 gallon Ziplock bags. This way moisture, dirt, etc. does not get into your freshly cleaned carburetor.
If you have any questions, please let me know. Also, if you enjoyed this post, please share via social media. Thanks!
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