Carberator Idle System..

what is the carberator idle system..??
what does it do in the carberator..??
how does it help???

Carbs have two or more circuits or paths of fuel flow. They are simply designed to operate at different points. The idle circuit is a path for fuel and/or air to flow that is used when the throttles are closed. You set how rich or how lean you want the idle to be by turning screws which move a tapered needle in or out of an orifice.

Then once you open up the throttles, there is another, larger needle and orifice that controls part throttle operation. Many have another circuit that comes into play at wider throttle angles.

to expound on this, there is many different ways they skin the cat. The important thing to remember about carbs, there will be multiple circuits that apply fuel/air for a given situation, and although they are different, independant circuits, they overlap each other.

The reason thats an important point, when you are diagnosing a problem or tuning for modifications, its important to always remember that just because you have a porblem at X range, and thats where Y circuit is supposed to be prominant, that doesn't necessarily mean Y circuit is the root problem.

But for the direct question, as curtis mentioned, the idle circuit's main job is to handle air/fuel ratio at idle, and usually has a large effect on partial throttle. From there its effect tapers off.....most of the time