Topic: idle mixture air screw question

[screemn2]

alright guys it seems that im kinda getting different info here or there would love to clear the air ....the adjustable screw on the bike carburators idle air screw i thing it is called ..when turning this screw out , counter clockwise , does that ritchen up the mixture or lean out the mixture ...soo, say a carb stock 'recommended setting' is one turn out ...if i turn it in does that richen the mixture or lean it out ...im working with the pd46c carb ....any facts are appreciated ...thanks to all

[Deltarider]

different info

This has to do with the difference in design between the oldtyle Keihin carbs and the later PD carbs like yours.
On oldstyle Keihin carbs (022A, 069A, 087A, 627B, 649A) turning the air screws in (clockwise), gradually closes off air making the mixture richer.
The IMS screws on PD carbs like yours on the contrary by closing off both air AND fuel as the screw is turned inward, has the effect making the mixture leaner.
 

[Scott S]

 The best way to remember is that if the screw is on the air box side of the carb, it controls air. If it's on the engine side, it controls fuel. 

[screemn2]

thanks deltarider...i have the 722a on my 1973 350g and the pd carb on my 550 project so they are both different from each other turn in for richer on the 722a and the pd turn out to make richer .....got it and thank you ...ok airbox = air adjust ....intake = fuel adjust ....hmmm just looked at mine 722a on 350 is intake side as well as the pd46c......

[flybox1]

....hmmm just looked at mine 722a on 350 is intake side as well as the pd46c......

(Yes, for your 350 carbs the screw meters AIR out=lean, in=rich)

On PD carbs, the mixture screw is on the engine side of the carb slide.  It meters fuel.
IN closes the circuit = leaner
OUT opens the circuit = richer

[dusterdude]

What scott said

[screemn2]

Thanks guys appreciate the answers...but again we have two different ones ...both screws on these teo different carbs are on the intake side of the carb...with what scott is saying that would meen thaton both carbs it is for fuel richening turning counterclockwise ...and flybox you are saying these carbs are opposite from one another...

[flybox1]

post up a picture of your #1 or #4 carb, as its installed on the bike, and you're standing to the side of your bike.

[flybox1]

PD carbs
FUEL screws circled are on the ENGINE side of the carbs

[harisuluv]

screemn2 you don't have to keep making multiple threads about your carbs.  make/keep just one, put your bike specs in the first post.  You have been asked repeatedly for pictures.  People still don't even know what bike you're talking about sometimes.  You are really doing yourself a disservice and IMO it is rude to the people that continue to help you in your threads.

You can post pictures/video.  This is the year 2015.  Surely you have access to a device that can take pictures/video. 

[screemn2]

Gotcha....wont post no more...ill just read and try to figure out stuff from there..

[flybox1]

go easy, man.  that's not what he meant.   
you have two threads with basically the same topic/issue.
just stick to keeping it in one thread.....that's all.  it allows those who are helping, to not have to bounce back and forth between threads, and it helps the noobies who might be having the same issues work thru it in one place.  how will they know to jump to another thread to find the one bit of info they need?

as I pictured above, are you PD carbs not similar in layout?