Coughing in an 883 Sportster has several crude names and can be symptomatic of several minor problems, all of which are easily diagnosed. These are almost always carburetion problems. The carburetor is hidden under the air cleaner, which is the almost always shiny, 8- to 12-inch-wide bump under your right hand as you sit on the motorcycle with your arms dangling. The air cleaner and carburetor are between the two, finned cylinders that form a V. Novice mechanics might not want fix all of these possible problems themselves. They can at least discover something intelligent to say to the service writer or Harley technician.
1. Open the petcock, fully extend the choke, put the transmission in neutral and start the motorcycle. Push the choke halfway in after 30 seconds.
2. Allow the motorcycle to run until the rocker covers, which are the chrome boxes on top of your cylinders, are very warm to the touch. Listen for coughing.
3. Push the choke completely in. Twist the throttle about halfway open and release. Repeat two or three times.
4. Listen for coughing. If the motorcycle coughs when the choke is pushed in but not when the choke is pulled out, your motorcycle is running too lean in what mechanics call the “idle circuit” because there is too much air and not enough gasoline in your fuel-air mixture. The idle mixture screw on the bottom of your carburetor is improperly adjusted.
5. Examine your air cleaner cover. If your air cleaner is original equipment it will be secured with one Allen bolt in the middle of the cover and will be marked “Harley-Davidson.” If the air cleaner cover is not original, your air cleaner assembly may have been replaced.
6. Examine your motorcycle exhaust. If your motorcycle exhaust and air cleaner are both not original equipment, your Harley 883 may need to be rejetted. The standard low speed jet on an 883 Sportster is a Number 42. You may need a Number 45 or a Number 48 low-speed jet.
7. Loosen the Allen bolt in the middle of your air cleaner cover with an Allen key or wrench and remove the cover. Find the spot behind the carburetor where the carburetor mates with the intake manifold.
8. Spray carburetor cleaner on the intake manifold while your motorcycle is running. Do not spray into the air cleaner. If the idle changes speeds while you spray carburetor cleaner only at the intake manifold, you have a leak there. You need new air intake seals.