All Harleys, including your Harley-Davidson 883 Sportster, are fundamentally simple machines. They move because an electrical spark ignites a mixture of gasoline and air in a cylinder. The resulting explosion drives the cylinder down. The linear motion is translated into a circular motion that eventually turns your rear wheel. Your Sportster will not run when there is no spark, no air, no gas, no expulsion of the exhaust that results from the explosion or when any of all that is not just right. If your Sportster won't run, walk up to it and do the following.
Inspect the spark plug wires on the left side of the bike just above your engine. Trace the wires from a rectangular box, called a coil, under the seat to the spark plugs which stick out of the tops of your cylinder heads. Push loose connections back together with your fingers.
Unscrew your spark plugs from the heads by turning them counterclockwise with a padded spark plug socket and a socket ratchet or breaker bar. Remove the plugs and examine them. The spark plug electrodes should be light gray or tan.
Clean plugs that are fouled with a nail file. Measure the distance between each pair of electrodes with a feeler gauge. The electrodes should be .040 inch apart.
Correctly gap the spark plugs with a spark plug gapping tool, as needed.
Remove the Allen bolt and washer that connect a tab on the back of the seat to the fender. Use an Allen wrench to turn Allen bolts. Pull the seat up -- and back -- to remove.
Bridge the positive and negative terminals on the battery with a 12-inch length of insulated wire. Ensure the connection sparks.
Examine the battery terminals and cables. Clean corroded cables with a small wire brush. Charge batteries that do not spark with a motorcycle battery charger for four hours.
Replace the seat. Bolt the fender tab to the fender. Shift the motorcycle into neutral.
Open the gas cap. Visually inspect the tank to ensure it contains gasoline.
Open the petcock. Fully extend the enricher knob. Start the motorcycle. Push the enricher knob halfway in after 30 seconds.
Push the enricher knob completely in when the top of the engine under your right hand becomes warm to the touch.
Twist the throttle and allow the Sportster to run. Release the throttle. If the engine dies the throttle speed or the fuel adjustment screw are improperly adjusted. If the engine dies turn off the motorcycle.
Unfasten and remove the air cleaner cover on the right side of the motorcycle with an Allen wrench for carbureted motorcycles. Remove the air cleaner under the cover using a Torx wrench.
Turn the throttle while you stare at the right, upper quadrant of the carburetor. Observe the throttle cam that is mechanically connected to the throttle with the throttle cables.
Start the motorcycle. Use a flathead screwdriver to adjust the idle speed upward until the motorcycle will continue to run without stalling.
Turn off the motorcycle. Replace the air cleaner and the air cleaner cover.
