Motorcycle engines need a source of ignition to run and that's the job of the spark plug. Spark plugs are produced with 8, 10, 12, 14 and 18mm diameter threads; the thread reach can also vary in length. Modern motorcycle engine designs often place severe constraints on spark plug design and positioning within the combustion chamber. The available space for locating the spark plug is ever decreasing due to increased valve sizes, larger coolant passageways and more recently, fuel injectors.

If you want to replace your spark plug make sure there is no debris around the plug prior to removal. Before inserting a new plug, make sure the threads in the cylinder head are clean and in good condition. Install the spark plug by hand until it seats