Cv carb

i know this isnt a new problem or thread but im new to the site and looking for some quick advise i just bought a 96 sportster 1200custom and it is running like crap poor idle spits out carb and blows black out exhaust if u get pass that its runs ok still not great but mostly quarter to half throttle and gets wosre as it warms up any info would help been threw carb and cleaned it all

How does the bike work with the air intake & filter completely off?

havent rode with cleaner off but maybe its not getting worse as it warms maybe its getting worse cause the gas getting on filter thats a new thought for me but it does run bad when its off just always put it back on for the test ride ill try leaving it off and see if makes any difference also gonna check vacum leak when i get home tonight.ALSO it hasent run right since i got it so not sure if any mods have been done to affect this.

Black smoke out the tail pipe?? That is an indication of rich fuel condition.. Do what everyone suggests, but keep an eye on what jet sizes are installed, let us know.

As others have said, check for intake leaks. Make sure carb is really cleaned out good and that the float and float needle is set properly.

Here's some light reading on the CV carb. May help.

http://www.shovelhead.us/pics/sheets/tech_cv_carb.PDF

I have the same issue except it is a 98 FXD I just bought. It wouldn't even stay running so I got it for $4200. So I rebuilt the carb with a kit from cvperformance and also added a K&N hi-flow system and V&H 2 into 1 Pro Pipe. On a fresh set of plugs it'll fire right up, and for about 45 seconds it'll sound great, but then it'll sputter, spew a bit of black smoke, and stop. I remove the air cleaner there is fuel dripping down the air cleaner back plate. I also replaced the slide as the old one looked like it had melted the plastic part holding the diaphragm. The plugs get a shiny varnish look. 1) Could this all be due to a bad or incorrect float setting? 2) The folks that sold me the bike tried to jump it off the starter. Could this have hurt anything electrical. 3) Can it be statically timed the way I used to do my 71 XLCH? 4) Suggestions?
Thanks in advance.

i have acually been threw carb already and has a new accel pump diaphram but today i will check for intake leaks and im goin to put a new float needle in it and replace spark plugs so i will post my results later on what i found thanks everyone

I have never had these issues myself but from reading, make sure that the rubber diaphram is not torn and it is seated properly for reinstall. Just curious, have you ran any carb cleaners through the gas to see if it knocks anything loose??

Was the carb dirty? I had a very similar problem with one of my dirt bikes. I cleaned the carb and put everything back together, only to have it foul again. Turns out the tank had rust from the gas cap that kept jamming the float open. Since it is a '96, you may want to drain/rinse the tank anyway. Check your cap, and fuel filter, too.
:cheers:

well i found intake leaking and change fuel bowl needle and some spark plugs she is runing alot better but still is getting to much fuel on initial take off the slow jet is 42 i think hard to read and main is 178 im gonna see if i can drop the needl valve down and lean out a little also gonna check my timing tonight to see if any body scewed with that

o yea forgot to say fixed intake leak and changed fuel filter any ideas would be great running out of options

not sure what enricher is i would guess u r talking about accel pump if not please let me know and i cant find any air screw read something about drilling out a plug on carb and installing a air screw

also when air fiter is off and start to crack throttle u can watch fuel and air go by needle and it seems to me that it is to much fuel passing the needle and the mixture is very turbulant it looks like a blown out fuel injector on an old chevy throtte body the mist is more like someone pouring it in to carb

The enricher is a fancy name for the choke.

CV Carburetor Modifications

HarleyHelp.com - cv carb

Fuel / Air mixture screw. You will need to remove the aluminum "anti-tamper" plug that covers it. Carefully use a 1/8' drill bit to make a hole in the aluminum plug, then pull it out. The only thing you gain by replacing the screw with the "thumb screw" type is ease of operation.