advice on jetting for new exhaust

I know this has probably been asked a jillion times, but with my limited research I didn't really find a lot. BTW, I'm more familier with Vtwins and have jetted a few from "package jet kits" such as cobra and dynojet.
What I have done is taken a saw to a perfectly fine tuned running completely stock 1982 XS400 Heratige Special. I just completely rebuilt these carbs and synchronized them to factory specs and the bike runs like a champ for the past 200 miles with the stock exhaust. Tonight I hacked the mufflers and installed a set of Emgo shorty mufflers onto the headers. Fired up the bike and she stumbles pretty bad, but once warmed up it smooths out over 3,000rpm, but it won't idle at all....... Give me some advice? Will simply adjusting the idle mixture screws clear this up? Or do I need larger pilot jets? Do you think I'm running lean or rich????????

I posted this last night and realized i was in "shops" and not in "garage" ... any advice is greatly appreciated.

I just edited my post above. Seems my phone wouldn't copy and paste all of my post from the "shops"

the way to go is you first try adjusting your idle mixture screws. Use Houghmade's post in this thread. If you can't get it to run well enough with that, get some new (bigger) pilot jets. You're probably running rich since the emgo mufflers provide less back pressure.

in this list of how-to's there's one of my old threads somewhere about fine tuning the carbs. In there Dave links to an external carb jetting guide which is excellent. You could use that if you want to go further and optimize your carbs for the whole rpm range, since the idle mixture screws and the pilot jets don't cover the whole range of rpm's. The change in exhaust back pressure does.

Running lean with less back pressure. But that should only effect high RPM (main jet), where there is much more exhaust gasses flowing.

Thanks for the info guys! I know this pic sucks, but you can see the mufflers that i went with.....i just opened the carbs becouse i didn't remember what jets were in there. looks all stock with 135 mains and 42.5 pilots...about to place my order with MikesXS along with some exhaust gaskets.

Cutting up your exhaust definitely messes with your idle. I've experienced it myself with my rotten H-pipe.

Bill, have you tried adjusting the idle mixture screws already? You might not need bigger jets

I did. Could have probably been ok after resync, but I'm a stickler on perfection. I need new adjustmrnt screw anyhow and have already tore back into the carbs, so I'm going to monkey with it.

I just ordered a pair of emgo cherrybombs..$59.. Had to jack your exhaust.lol mines gonna be a lil longer.

Not sure where but I just red in the past few days here about a company that will set you up with a set of jets. They do need some info from you about your bike build but it's been said they have a handle on this black art that is Motorcycle carbs. I think they are also on Ebay.

Yea, i posted a link from them in the shops asking if anyone had dealings with them. ....i figured the advice from guys here and MikesXS would be better....i ve got plenty of time to tinker on this machine so I'm up for the challenge.....NewBuilder, these mufflers sound good. in my opinion they look grratgreat. too too.

Cool that was you. I'll have to check into this subject some time as well. But since it's -9f here in the great frozen north woods I think it can wait. Nothing worse than working on cars trucks snow blowers etc in an un heated garage at these temps.