hi. we know that our pilot screw is kind of a fuel screw which adjusts the fuel amount in the mixture which is used by the engine while it's idling. we have a separate air jet (one of the two air jets) for that circuit too.
but when i removed the pilot screw completely and looked in to the well where the screw was seated, i could only see one tiny little hole. i couldn't see any other hole where the air apparently enters. so if there's one hole the air+fuel should enter as a mixture? but then how the pilot screw only adjusts the fuel amount?
if someone can explain, it will be much appreciated. thank you

 

Have a look at this video, it shows the bypass tube from the air side of the carb, which bypasses the throttle valve and mixes with the petrol that it draws from the idle side of the bowl, look at the video from 4.50 , shows it quite well

 

thank you CaBaRet. yea i've seen that video several times
the problem is, in our carbs the pilot screw it situated just under the carb throat with an angle. if we look through the idle port we can see the pilot screw tip clearly. the tip goes to a hole which is located at the very bottom of the pilot screw well. i don't see any other hole there which may provide a specific air volume to the mixture separately.
thank you

 

I think that you are over thinking it, as the idle screw is only for that at this stage , the only other variable is the slow jet size, with the throttle shut the vacuum is created through the slow air side as the cylinders suck the air in ,it passes over the fuel port sucking petrol with it (from the slow jet)into the cylinder, that's why factory settings of slow jet and pilot screw should offer the correct kind of mixture for the cylinder, if you change pilot screw settings along with slow jet settings it will never run at optimum

 

yea got it you are correct i think i'm overthinking it.
actually the reason for think like that is there's only one hole inside the pilot screw well which is also connected to a slow air jet (through the slow jet). we can clearly see it when we spray some carb cleaner through one of two slow air jets. anyway even though it emits a mixture (not just the fuel) the manufacturer may have made it to become rich when we allow more amount of mixture (pilot screw out) to the cylinder and also to become lean when we allow less amount of mixture (pilot screw in).
thank you for the information

 

Truly think that bench setting a set of carbs is good practice, gets you really familiar with your carbs (not all the same) and there are plenty of good video's on You Tube, over time any knowledge is good knowledge ,just a matter of taking what you need

 

true actually this forum helped me a lot than youtube. there are many threads with pictures regarding carburetor questions and explanations at the same time so it's very useful