The carburetor on this Harley is the round, chrome device between the two pipes.
An FXST is a kind of Harley-Davidson motorcycle. F means “big engine motorcycle” and X indicates “sport.” The original FX in 1971 was assembled from F and X parts. “ST” stands for “Softail,” which is a suspension system without visible shock absorbers. This bike was manufactured before 2007 because starting in that year all new Harleys came equipped with fuel injection. The carburetor, or carb, is a constant-velocity Keihin carb and it is easily replaced in one lazy afternoon.
1. Put the motorcycle in neutral and ensure the petcock is closed. Start and run the motorcycle until it coughs to a stop. Attempt to restart the motorcycle to ensure that the carburetor is completely out of gasoline.
2. Reach under the fuel tank, just in front of your left knee, and unclip the enrichener knob. Let the knob and cable hang free.
3. Loosen the air cleaner cover bolts. The air cleaner is between the cylinders and the original cleaner is either round or elliptical depending on the year of your FXST. Remove the bolts using either a Torx or Allen socket, depending on the year of your bike and whether you have already replaced this cover, and a socket wrench.
4. Pull out the two breather tubes that plug into the body of your air cleaner and let them hang free.
5. Unbolt and remove the air cleaner, which contains a metal or paper filter, using either a Torx or an Allen socket and a socket wrench.
6. Loosen the fuel line hose clamp with a flat-head screwdriver and pull this tube from the body of the carburetor.
7. Follow both throttle cables from the throttle to the carburetor throttle cam. Mark the front and back cables with masking tape and a pen, then unscrew and disconnect both cables. Let those cables hang free.
8. Unbolt and remove the air cleaner backing plate with an Allen socket and a socket wrench.
9. Rock the carburetor from side to side and pull it out of the black, rubber boot that connects the carburetor to the intake manifold. Gently pull the enrichener assembly through the engine and remove the carburetor and enrichener assembly as a unit.
10. Unscrew and remove the enrichener cable from the back of the old carburetor. Screw the enrichener cable assembly into the same location on the back of the replacement carburetor. Hand-tighten the plastic cable sealing cap.
11. Snake the enrichener knob and cable through the engine under the fuel tank. Seat the new carburetor in the intake manifold boot.
12. Replace the air cleaner backing plate with an Allen socket and socket wrench. This is the plate that actually holds the carb to the engine.
13. Replace both throttle cables on the throttle cam exactly as they were when you started. Remove the masking tape.
14. Replace the air cleaner and the air cleaner cover using either a Torx or an Allen socket and a socket wrench. Re-secure the enrichener knob into the clip on the left side of the motorcycle.
15. Replace the breather tubes. Start the bike to ensure it runs before replacing the air cleaner cover.
16. Replace the air cleaner cover using a Torx or Allen socket and socket wrench.