What size wrench is used for motorcycle spark plugs?
2 Answers
Motorcycle spark plug installation and removal require a 17mm wrench. Steps for replacing motorcycle spark plugs: First locate the cylinder head position, find the spark plug cap, and remove it. Before removal, you can use an air gun to clean the surrounding area to prevent debris from falling into the combustion chamber through the installation hole when removing the spark plug. Use the onboard/special tool to unscrew the spark plug counterclockwise. If no dedicated removal tool is available, you can also use a wrench to turn it counterclockwise. Hand-remove the spark plug body and begin inspection and cleaning. Since onboard tools lack magnetic attraction and a fixed base, the spark plug may drop during removal. After removing the spark plug body, install the new spark plug along the original path.
I used to tinker with various motorcycle engines all day long. The spark plug wrench usually comes in 16mm or 18mm socket sizes. Japanese brands like Honda or Suzuki commonly use 16mm, while European and American brands like Harley might use 18mm. It really depends on the model—for example, small-displacement scooters generally use 16mm, but large cruisers are a different story. I recommend using a specialized magnetic wrench to prevent the spark plug from falling into the cylinder bore. Always let the engine cool down before removal or installation to avoid burning your hands. Regularly checking the spark plugs is crucial—excessive carbon buildup on the electrodes affects ignition efficiency, leading to higher fuel consumption or starting difficulties. Replace them every 10,000 kilometers, and the torque setting should not exceed 18-22 N·m, or the threads may crack. If unsure, consult the owner’s manual or ask an experienced mechanic. While DIY work can be fun, never overlook safety details—wearing safety goggles is a wise precaution.
