The Jet Needle controls the fuel mixture in the mid-range 1/4-3/4 throttle positionThe taper of the needle determines the amount of the fuelFor example: the thinner the diameter of the needle, the more fuel will be drawnThe thicker the diameter of the needle, the less fuel can be drawnThe Jet Needle controls the fuel mixture in the mid-range 1/4-3/4 throttle position The taper of the needle determines the amount of the fuel For example: the thinner the diameter of the needle, the more fuel will be drawn The thicker the diameter of the needle, the less fuel can be drawn 10mm - 2.51 20mm - 2.51 30mm - 2.51 40mm - 2.41 50mm - 2.18 60mm - 1.49 Original TM38 Flatslide