The jets control the amount of fuel that is fed into the carburettor to be mixed with air. The size of the main jet has a decisive impact on engine performance; a jet that is too large makes the mixture too rich, one that is too small makes it too lean. The colour of the spark plug indicates whether the mixture is ok, it should be a light tan. We recommend the purchase of a complete carburetor jet set with 8 or more different sized jets, so you can adjust your carburetor optimally. The choice of the right sized jet can have a positive or negative influence on performance, and we offer various sizes and types.