A pilot jet for the 6 and 9 series of carburettors, and the MK2 . Many of the four stroke carbs are fitted with a fixed size bush instead of a pilot jet. This can be drilled out and tapped to accept a pilot jet. The 2 stroke concentrics normally are fitted with a pilot jet. In the MK2 this jet was used as both the pilot jet and the cold start jet. Similar to original part number 124/026. Please choose your preferred size from dropdown.