Replace Spark Plugs On A 2000 Sportster Xl

Twin piston Harley engine

Nothing runs quite like a Harley Sportster. Small, quick and powerful, the Sportster is the little Harley that could. To keep that Sportster engine running smoothly requires regularly replacing the spark plugs. When properly gapped and installed, new spark plugs can smooth out a rough running engine and improved power and efficiency. The service manual suggests replacement every 10,000 miles, but according to Benny Miller, certified Harley mechanic for Renegade Cycle in Mesquite, Texas, spark plugs should be replaced every 3,000 miles, or every oil change, to insure peak performance. It takes only a few steps to replace the plugs.


1. Turn both ignition and kill switches to the “off” position. If the Sportster has been running, allow the motorcycle to cool before proceeding to avoid burns.

2. Locate the spark plug cables on the left side of the Sportster, just below the gas tank protruding from the cylinder head. Using needle nose pliers, grasp a spark plug cable at the thickened base near the cylinder. Avoid pulling on the cable above this protected base as it can damage the internal structure of the cable. Pry upward, removing the spark plug cable from the spark plug and the cylinder. Note which cable goes to each cylinder to avoid crossed wires.

3. Place a 5/8-inch spark plug socket over spark plug. Attach a 3-inch ratchet extension and ratchet handle. Turn the ratchet in counter-clockwise direction. Continue turning until the spark plug comes loose from the cylinder head. Examine the old plug for signs of oil deposits or engine wear. Check the threads inside the cylinder for deposits or corrosion. Use penetrating oil to soften any deposits and a thread chaser to clean the threads.

4. Gap the replacement plug by placing the electrode opening of the plug over the narrowest part of the gapping gauge. Slide the plug opening until it is even with the correct gap size. A 2000 Sportster should be gapped between 0.038 to 0.043 inches (0.96 to 1.09mm).

5. Apply a light coat of antiseize lubricant to the threads of the replacement spark plug. By hand, place the spark plug into the cylinder head opening and turn clockwise, hand tightening it until it resists. Avoid cross threading the plug. Place a5/8-inch socket over the end of spark plug. Using the socket wrench, turn it clockwise until the spark plug becomes snug, usually another quarter turn. Do not over tighten.

6. By hand, place a spark plug cable over the appropriate spark plug. Push downward on the cable until it will no longer depress.

7. Turn the ignition switch on. Make certain the motorcycle is in neutral gear. Turn the kill switch to the “on” position. Depress the starter switch until the engine starts. Listen for any abnormalities in the rhythm and idle speed. Adjust the idle as necessary.