Motorcycle Repair: popping at idle

Question
Hi, I have an 05 Honda Shadow Spirit Vt1100. It has a stage one jet kit installed with aftermarket exhaust. It has been running perfectly with this setup for two years. Two days ago, I noticed popping coming from the rear cylinder only at idle. There is no problem on the highway. Thinking it was an air leak,I checked the head bolts at the crush gasket and the carb boots. All ok. I then ran the A/F mixture screw in to seat and back out 21/2 turns. I started the bike no problem but it still pops on that cylinder. here is the odd thing, if I turn the A/F mixture screw in to seat while the bike is running, there is no change in rpm. When I do this for the front cylinder, the rpm changes immediately. I have a shop manual but this is not on the troubleshooting page. I have no problem removing the carbs as I put the jet kit in.
Thanks for your help.
Tony

Answer
I think there is something in the Carburetors clogging the Slow Jet which
it uses to Idle. Pick up some SEAFOAM at the auto parts store and use
it only per Instructions. This might dissolve or Help remove what blocking that jet.
If that don't solve the Issue then the Carbs should be removed and Cleaned... Joe