How To Tighten a Spark Plug on Your Motorcycle

By Walter F. Kern

Most do-it-yourself motorcycle mechanics change their own spark plugs. Most also don't know how much to tighten them to seat properly.

Here's How to Tighten a Motorcycle Spark Plug:

  1. Ensure that the area around the spark plug hole is clean before removing the old plug.
  2. Make sure the threaded area of the new plug is clean and dry. Resist placing any oil or WD-40 on the threads.
  3. Insert the plug making sure that it is threading correctly. You don't want to damage the hole by cross-threading.
  4. Tighten with your fingers until you feel the crush washer starting to seat at the bottom.
  5. Tighten 1/4 to 1/2 turn more.


  1. If you have a torque wrench and can find a specification in your owner's manual as to how much to tighten the spark plugs, use that value with your torque wrench to tighten the plug.

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