Off idle up to midrange fuel/air supply is through the pilot jet, the smaller of the two jets in carb body. Jets screw into jet holder, and the holder tube is an emulsion tube. This tube furnishes air at 90 angles to flow of fuel through cross-drillings, to purposely upset flow path. By that it makes a better emulsion of fuel & air to atomize gasoline into a gaseous fuel/air mixture.

There's a tiny hole through center of pilot jet [and main jet] that must be opened, and the jet holder/emulsion tube has a tiny hole at farthest end too. A very fine jet cleaning wire must pass all the way through both. If it will only pass through one end, then soak & soften and gently twist the jet cleaning wire through.

All air bleeds in carb also need to be cleaned with solvent, spray carb cleaner [goggles] & jet cleaning wires: 2 at inlet throat, one in venturi tube below slide piston, and one more at rear in carb throat right in front of intake maifold. When you're done, with carb completely disassembled, spray carb cleaner when shot through the plastic wand into jet, jet holder or air orifice should exit somehwere else in fuel/air circuits, not just spray back from wand in hole. If it doesn't spray on through to somewhere, you're not done yet.

Idle/pilot jet mixture is set by the fuel mixture screw in carb body close to intake manifold. Initial screw position setting is about 1-1/2 turns out CCW. Turn it CCW to highest smooth idle, then count your turns as you turn back CW to engine just beginning to stumble. You may then set idle to 1/2 way between those two points [Lean best idle] or back to highest smooth curb idle [Rich best idle]. Experimentation will then reveal which setting your particular engine/carb likes best.

If you make your own jet cleaning wires instead of buying a jet cleaning wire assortment, like using a guitar string etc. then be sure to dress the end of cleaning wire on some emery so it's very smooth, with no nibs sticking out to score or scratch jet interior passage. 

Last Edited By: XLerate Mar 7 11 7:52 AM. Edited 2 times.