Jetting Your Carburetor: Part Four

Now that we’ve covered the two primary circuits of the carburetor, the final components to review are the pilot jet and the pilot screw. These mechanisms control the flow of fuel and outboard motor oil in a two-stroke engine when the throttle is in the idle position up to one-eighth open. Much akin to the main jet, the pilot jet is essentially a screw that is equipped with a calibrated hole.

Like the other two circuits, a high number on the pilot jet indicates a larger opening and a richer mixture of fuel. The pilot screw works like the one on the main jet; tightening the screw makes the mixture leaner, and vice-versa. By adjusting the three circuits that we have covered over this week, you will be able to fine-tune the richness of your fuel to air ratio and customize how your engine runs.