Looking for carb info..

[1quikvento]

Ive read plenty of times about moving a certain clip in the carb to make it more rich or lean depending on which way you go-up or down. I was looking thru the carb and intake section of the tech library and couldnt find info on this procedure. I would like to check mine, but have no clue where this clip is that has an adjustable clip.

Is it the needle valve we're talking about?can someone send me a link?

[reveeen]

www.dansmc.com/carbs2.htm

Specifically:
www.dansmc.com/jet_needle1.jpg

(noticing the position clip is in the 2nd richest position, or in the second from the bottom groove)

Typically this is the last adjustment you make to a carburetor. The first being the idle adjustment (or air screw), the second being the main jet size (for WOT operation), this one only affects mid range operation (or partial throttle, roughly 1/4-3/4 throttle), moving the clip down (or the needle up) for richer, or the clip up (needle down) for leaner.

To further confuse the issue: the makers of "performance carburetors" will sell you needles with different tapers to overcome specific tuning problems.

Enter the "power jet".
Mikuni offers power jet kits, so does Klein, OKO carbs come with, and without...... what are these things?
They are a separate fuel feed from the float bowl to introduce extra fuel into the mouth of the carburetor in "high demand" situations (usually 70% throttle to full throttle situations). Some swear by them, some at them. You don't necessarily need one if: your carburetor is tuned properly and is of a sensible size.

[brandonscoot]

yes!!! this is the info i am looking for too. i just need some time to savor all of this and absorb it. then let the tuning begin!

[1quikvento]

hell yeah that was much help. So say my clip is in the center position to begin with. And moving that clip one notch down will raise the needle(and raise the taper allowing more of the mixture to pass by it as it flows through the venturi), correct? I think i can understand that now..

[Fox]

Lowering the clip allows a little more fuel in to interact with the air stream at wide open throttle. (richer with gas) That doesn't automatically mean more power. it can hinder performance depending on your setup. Raising the clip leans out the mixture.

An engine is really an air pump if you think about it. The air/fuel mixture provides the power to run the pump. The more efficiently you burn the fuel the more power a given displacement will have. If you open up the intake and exhaust ports and install a bigger jet then the pump will flow more air, have more horse power/torque and run at a higher RPM. A bigger piston kit requires even more jet etc.. Brent, 190mech, Robert and a few others here could explain it in scientific terms but you get the basic idea I hope.