carb popping

Hello everyone,
I am new to this site and thought that this would be a good place to get an answer to a question about my bike so here goes. I have a 2004 1200 Sportster with 5200 miles on it. When I got it, it had 3100 miles on it and I always had a problem with it popping through the carb. I installed SE pipes on it and took it to my local Harley dealer and told them that I had a proplem with the popping through the carb. The mechanic told me that he could rejet the carb and that would take care of the problem. I also told him to put it on the dyno and get everything set up right. When I got it back I rode about 10 miles. When I went to down shift I hit the throttle before I shifted and pop goes the carb. I took it back the next day and he recaled the ignition and said that would take care of it. Well it didn't so I took it back again and he adjusted the carb again and again he said that will take care of it. (NOT). I called Harley and they said they could not help me so I hope someone out there can. I can ride all day long and no problems then all of a sudden it might pop 3 times in a row when I rev it up and then it would be good the rest of the day. The mechanic told me he does not know what else to do. So you see I am stuck. Don't know which way to turn. Hope you can help.

Popping

Popping out the carburetor ? do you mean back-fire ? the only thing I can add at this point is check for the obvious, like intake leaks, check plugs,wires and timing If possible, swap with an KNOWN GOOD carb, and if that don't do it, then swap with known good ignition. Good-luck

Yep that is what I mean. Backfire. I had the timing checked and re-caled by a Harley dealer. The carb was gone over and the bike was put on the dyno. Wouldn't the dyno pick out any problems with the carb or ignition? What I don't understand is why it only does it now and then. The bike runs like a raped ape out on the highway. It just does it when I rev it to down shift or when I pull out, but once I am going it will not do it. I hope I explained it a little better. Thanks for the reply.

What you are describing sounds like lean pop to me.

If the pilot is to small or adjusted too lean, you will get the off idle pop and a decel pop.

It is basically caused by the overly lean Carib settings used to meet EPA rules.

Also, a very fast blip of the throttle can cause an occasional pop.
Since your local dealer has not been able to get it fixed, try a well known independent shop.

I will try that. There is a small shop close to me that I have been told that he is very good. I was hopeing that the dealer could get it fixed after putting over $600.00 into this carb and setup so I will try this other guy and I will let you know how I make out. I want to thank you all for your help.

Does it do it if you just shift down without the throttle blip?...You know thats not necessary and as far as I know serves no purpose other than to make more noise from engine braking when you go to a lower gear.

No it does not do it on just down shifting and you are right about the blip with the throttle but I like to make noise but it will do it sometimes when I just give it throttle to pull out.