My 2004 sporty has the carb cough issue, so I followed the directions on Harley Performance site and attempted to adjust the idle mix screw first. The plug in my carb was rubber however and it made me think that someone had already adjusted the mix. I ended up turning the screw out past 6 turns without resolving the issue, so I decided a rejet would be next.
I picked up a 45 pilot jet, planning to use it in place of what I believed to be the stock 42. When I pulled the pilot from the carb it read 48, the main jet is a 190. So it seems my carb had already been rejetted. Aren't the stock jets 180 & 42?
So the question is - should I just clean and reinstall the 48 or try the 45?

 

What model do you have? And what mods?

Those two things are very important in determining the proper jetting.

 

It's an '04 xlc with a big sucker air cleaner. I'm running SEII slip ons also.

 

In your sig it shows a 1200 conversion, so using that as a basis, I would suggest a 45 pilot and a 175 main to start off with your mods. Set the screw to about 2 turns out and you will probably have to turn it in just a bit, but it will get you started tuning.

A 48/190 just sounds like absolutely way too much jetting.

 

Yea maybe your running way too rich

 

+1 - a 48/190 has to be way too rich unless you've done some serious motor work.
I'd suggest a 45/180 as a starting point for a Stage 1 04-06 1200. That seems to be the magic combo for the majority of those bikes.

 

I think you were that one that gave me that same advise sometime last year when I asked a similar question. That 45/180 combo is working for me on my '06 1200, I didn't mess with the needle, and as much as I played with that idle mixture screw, I kept coming back to 2.5 turns out. The 180 was stock in mine if I remember correctly. Zero coughs/stumbles/carb farts. I'd start there since it's only one jet change, and maybe try the 175 jet if it seems rich at open throttle.

 

So will a rich mixture cause coughs/stumbles etc? I cleaned and put the 190 and 48 jets back in and still experience the same problems. Shouldn't I have the mixture screw turned most of the way in?

 

A rich mixture can mimic a lean mixture to those not very atune to the differences. I honest to god would get rid of the 48/190 combo. That is big twin jetting, not Sportster. Go with the CHarley suggested 45/180 or my 45/175 at least. The difference is minimal.

I know for a fact that the 48/190 is wayyyyy too much jetting for anything but a highly modified sporty.

You want the screw between 1/2 and 2 turns. Any less and you need a smaller jet, more and you want a bigger jet.

 

Yea maybe your running way too rich