I own a 2006 FLST Heritage Carb model. When new around 200 miles, the bike would sometimes pop when you would give it gas to gofrom a stop, or downshift. This wasn't an all the time occurence...just occasionally, but anoying. I had a stage one kit installed by the dealer at the first 1000 mile service. They installed Python slip ons, and I believe the jet is a 185. The bike ran a lot better! BUT it still has the occasional backfire through the carb. It still happens at idle when you just hit the gas to go, or when you are downshifting. I had the bike dynoed and he said it's running perfectly for going down the road...It's about as perfect as it could get. He thought it was running a tad rich at idle speed and adjusted the carb a tad. I'm assuming he turned the idle mixture screw clockwise to lean it out a bit. He reached up under the center of the air cleaner with a screw driver.

My question....Is this normal? Is it running a little to lean again? Do I need to richen the mixture a little? (what's a little????1/4 to 1/2 turn?) I'm interested in all opinions.......This is my first harley and I love it, but want to get rid of the annoying pop....thanx in advance!!!!

 

Sounds like you need to turn the idle mixture screw out a little, but it's hard to tell how much from here. Get the bike warmed up good, andwith it idling turn the mixture screw out one turn. Hopefully, your idle speed will come up a little and it'll smooth out a little. Then turn the screw in about 1/4 turn at a time, waiting a few seconds between turns,until youhear theidleget ever so slightly rougher. Then turn the screw back out around 1/4 turn. If that doesn't fix it, you have other issues.

 

If you just put on the slipons, and nothing was done to your carb (removed and rejetted) I don't know how the mechanic can reach under your air cleaner and adjust the carb. It is sealed from the factory, and without removing the carb and removing the slow idle seal you can't adjust it.However if the plug has been removed, you can adjust the slow idle screw, just as Murphdog explained. This would be a good time to upgrade to a free flow air cleaner like a Ness Big Sucker and get complete performance of your new slipons. However you will have to rejet the carb a 46 slow jet, a sportster needle (or shim yours with washers) and change the 185 main jet to a 190 and 2 to 3 turns out on the idle screw. There are several posts on this forum and other sites on the internet that explain, and show you how to do it.
http://www.nightrider.com/biketech/hd_cv_mods.htm Your carb pops are usually a lean cond. 1/4twistof your throttle you are on the slow idle jet and idle screw mixture. 1/4 to 3/4 twist you are using the needle, 3/4 twist to full throttle is your main jet.

 

Since he said he had a 185 jet, I guessing the dealer put a Dynojet kit in it.