NGK Spark Plug for Harley-Davidson M8 and XG

NGK Spark Plug for Harley-Davidson Milwaukee-Eight and Revolution X

NGK plugs are right at home in a Harley-Davidson—for the money, many riders feel there's no better brand for a bar-and-shield bike.

• Choice of construction
  • Copper-core plugs offer great conductivity and strong spark and their price makes them an economical choice for riders who prefer spending the time to make more frequent swaps in order to combat the detrimental effects on the gap due to normal erosion
    • Direct replacement for the OEM plug in engines specified in the fitment section with the recommended heat range for listed applications
    • Conventional copper core plugs yield strong, consistent spark
  • Iridium plugs feature fine-wire iridium that some riders feel improve idle and acceleration, especially in motorcycles that have been tuned aggressively
    
    • They usually have a longer service life if the motorcycle's air-fuel ratio is correct at all throttle angles
      
    • Iridium is an especially compelling option for motorcycles like Touring models due to the additional labor required to access the plugs (the fuel tank must be removed) and the quantity of plugs (Milwaukee-Eight engines have dual-plug heads)
      
• Resistor suppresses electromagnetic interference so the ECM and other onboard electronics function correctly
• Trivalent metal plating on plug body
  • Resists corrosion and seizing in aluminum cylinder heads
• Corrugated insulator ribs help prevent flashover (when the spark moves along the outside the plug rather than inside it)
• Sold individually
  • Milwaukee-Eight engines have dual plug heads—order a quantity of four for a complete tune-up
  • Revolution X engines have single plug heads—order a quantity of two for a complete tune-up