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OS 46AX low speed throttle question

Old 10-09-2016, 06:18 PM
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Default OS 46AX low speed throttle question

Had to replace low speed (idle) screw in carb, what generally is the number of turns to screw it out for the correct low speed idle control? somehow when I tighten the throttle lever on the carb then I cannot turn the low speed screw. what am I doing wrong please? thanks reply to [email protected] or here.
Old 10-10-2016, 07:26 AM
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Okay, may not be normal but here is what I do to adjust the low end on most two cycle carbs.

1) Remove carb from engine
2) Set high end needle at factory recommended setting usually two and a half turns open
3) Make sure that your carb will close 100%
4) Open carb so there is barely light coming through, maybe a pin would fit through the opening. Sometimes easiest way is to set the carb barrel stop at this spot temporarily.
5) Place a piece of tubing on the inlet and blow air through it while slowly adjusting the low end needle until no air will pass thru at all. Then open up until you hear very minor amount of air going through. Barely should be able to hear it.
6) Reset the barrel stop so barrel will shut completely.
7) Put your carb back on the engine and give it a test. Should only need minor adjustment from there.
Old 10-11-2016, 07:25 AM
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Here is how I do it and I adjust my engines by ear!
First! I never never remove the idle speed needle from the carb or at least very seldom do it! Why doing it??
But if I do I just screw the low speed needle in some, start the engine (the engine is mounted in a plane), give full speed and then adjust the full speed needle for max rpm and then back off slightly.
I then throttle down and let the engine idle for let's say 5-10 seconds and then notice how the engine reacts when I give full throttle.
It could react in two ways! Either the engine will quit directly which means the idle needle is set too lean.
Or it could bludder and sputter and then the idle needle is set too rich!
From that information I go ahead and throttle down again and either set the idle needle richer or leaner...this is very easy to do and only take a few seconds!
Old 10-15-2016, 07:48 PM
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you have the NEW screw to far in. with the carb almost closed screw it in till it stops DO NOT make it tight. Then turn it out three full turns and then run the engine. Then a good way to set up low end before first run is by RCS. I however just tune mine with the engine running but not recommended as you are very close to the prop
Old 10-16-2016, 12:38 AM
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For the initial setting one can also read the manual:

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