I'm sure I'll get a straight answer here. I have CV 40 That has some fuel coming out where the needle goes into the emulsion tube at idle.If I hold needle up at idle ,gas stops coming out.Drop needle back in,gas comes out.Float level good.Float valve fairly new and looked good.Is this normal ?Thanks

 

Is this a new to you carb or has any work been done to the carb? How many miles on the carb? What is your idle speed? I would double check the float level using instructions linked below.

It's possible your needle jet is worn allowing fuel to be drawn passed it and the needle, however, keep in mind that the needle is not supposed to completely seal 100% in the needle jet.

I am guessing that the reason it goes away when you lift on the needle is you are raising the slide (making the inner diameter of the carb larger), creating less venturi (weaker vacuum) to draw the fuel so it stop or reduces. I am guessing you are raising the slide by hand to raise the needle.

If carb has some miles on it, my suggestion is to replace at least the needle jet and to closely inspect the needle for wear and possible replacement. Here is a nice link that covers the CV carb and it's potential issues:

http://sportsterpedia.com/doku.php/techtalk:evo:carb02

Here is a nice video regarding circuit function during the different carb conditions/demands:

 

Thanks for the reply Yankee Dog.
Carb recently rebuilt. 46 slow,195 main,#5 MAHR needle.Runs good but does not have that perfect idle at 900-1000 .Idle mix screw will not smooth it out. Float and float valve is good .No flooding,just a trickle of fuel being sucked out of needle jet at idle.Did some more digging and a few people have said there should be a small amount of fuel coming out at idle.Maybe I just never noticed it before..

 

I have a CV40 and the needle has never dripped gas at idle. it is also my understanding that the needle does not come into play until after the first 1/3 of throttle, therefore, this should not be the case at idle. If it does that with the bike off, then I tend to believe that it is your float. If it not the float, then change the needle to a known entity (same brand) to correspond to the emulsion tube.

 

​​Thanks.So if that is the case that might explain not being able to get a smooth idle.

 

I've been thinking about this. No offense, but did you use a protractor to gauge the lean angle of the carburetor? It is preferable to set at about mid range in the angle, or about 15 degrees. Do not check it free hand. It is best to use a protractor and then use a digital caliper gauge or other appropriate tool to set the bowl height. If the float is set too high, it is set too rich. If too low, it is set too lean. If it has a rich setting, that could account for the fuel that keeps flowing into the carburetor bowl because the float needle is not being allowed to shut off the fuel flow into the bowl. While you are in there, you might as well just change the float needle and blow out the hole to make sure there is no debris or crud keeping the needle from seating properly. At this point I really do not think the needle, jet needle, or emulsion tube has anything to do with it, it is simply fuel overflowing out the top of the carb bowl.