Refer to Maintenance Scheduling → Regular Service Intervals → Regular Service Intervals: 2006 Sportster Models. Check the spark plugs at proper intervals.
Do NOT pull on any electrical wires. Pulling on electrical wires may damage the internal conductor causing high resistance, which may result in minor or moderate injury. (00168a)
Disconnect spark plug cables from plugs by pulling on the molded connector caps. To reconnect, simply snap-on spark plug cables to tops of spark plugs.
Refer to Specifications → Specifications: 2006 Sportster Models → Ignition System: 2006 Sportster Models before servicing spark plugs.
  1. Check spark plug type. Only use those spark plugs specified for your model motorcycle.
  2. Check spark plug gap against table specifications.
  3. Always tighten to the proper torque. Spark plugs must be tightened to the torque specified for proper heat transfer.
If a torque wrench is not available, tighten plugs finger tight and then tighten an additional one quarter turn with a spark plug wrench.