Needle in the carb

Moving it up leans the motor out in the mid range. I have two Grubee GT-5 motors, one likes it in the top position and one likes it in the middle position. Go figure.

look at the carb and think about it a little. fuel from the float bowl is drawn into the venturi/carb intake. the tapered needle valve restricts/regulates the amount of fuel that can be drawn into the intake and mixed with air. when you rotate the throttle from idle to full throttle, you are pulling that needle out of the jet asssembly when you return to idle on the hand throttle, you are blocking the the jet assembly partially.

so, with that in mind, consider what moving the needle clip up one notch or down one notch does to the fuel mixture/fuel flow.

the lower the needle, the leaner the engine will be.