125cc Spark Plugs

The spark plug is the thing sticking out the top of the cylinder head. It ignites the fuel/air mixture in the combustion chamber.

There are many aftermarket, high performance sparkplugs on the market for 125cc motorcycles, but choosing the right one can be a nightmare!  Consult your handbook or the forums for the right one for your needs.  The basic benefit or performance spark plugs is to change the combustion temperatures and allow for higher compression ratio in the cylinder.  With the addition of other tuning methods, this can produce only slight gains, but does not cost the earth (you only need 1) and is worth while.