The mixture screw really only affects the idle more then anything. Until you know what jets are in it you are wasting your time

 

What??? I'm not sure where you get your info from, but let me help you out here.

Step 1. It is impossible to backfire in the exhaust system without something to burn being in the exhaust system.

Step 2. An overly RICH mixture burns cooler than a LEAN mixture.

Step 3. An overly RICH mixture can allow unburnt or partially burnt fuel to enter the exhaust system, because there is just to much fuel to burn in a short time, resulting in a fuel smell or black smoke. This is why when you smell partially burnt fuel, you can immediately say that an engine is running rich.

Step 4. Popping through the intake is caused by a LEAN mixture. This is GENERALLY because temperatures are high enough in the engine to allow combustion outside of the combustion chamber or while an intake valve is hanging open.

Step 5. None of this matters if you have a leak in the system anywhere.

Step 6. Go here
http://www.harley-performance.com/index.html

 

Yes, popping is fumes being burned in the pipe. It is caused by unburned fuel igniting in the exhaust, however it can be a result of both lean and rich tuning. Without a dyno you really have no clue what your mixture is.

Also, the burn rate is the same no matter if it is lean or rich.

 

My guess is you are running lean on decel....I had the same issue on my EVO when I had an air leak at the carb

 

+1 - Burn Rate is effect of Octane not mixture.

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You say you tuned it based on response, sound, temp etc... Have you checked your plugs?

 

If this is your knowledge of fuel mixtures and tuning, you need to find someone that knows and understands what he is doing.

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Ding! Ding! Ding! We have a winner. A good way to look at this is not that you're too rich or lean, but that the conditions are just right for unburned fuel to ignite when it hits the hot exhaust pipes. How does unburned fuel wind up there anyway? There is some overlap between the valves closing completely and some exhaust pipes actually can cause scavenging of the combustion chamber especially under high vacuum conditions like high rev / and no or little throttle decel. Anything that changes these "just right" conditions to less than perfect will cure the popping. That can be leaning it our or richening it up. We generally don't want to lean our bikes out as they're typically set up by HD to run too lean anyway, so most of us fix the problem by adding fuel to the mix.

On an injected bike this is pretty easy, there are custom maps for decel enleanment/enrichment, but on a carb'd bike you don't have separate jets for decel only. So you wind up making it richer....

 

When i installed my pipes, all i did was adjust the screw and it made a big difference but thank you for your reply

 

#1 It doesn't backfire, and your misunderstanding. I said fumes are being burned in the pipes
#2 Agreed, has nothing to do with what I said
#3 Agreed, but lean mixtures burn slowly, giving the fumes enough time to enter the pipes
#4 were talking about a exhaust making popping sounds not intake
#5 thank you for the info
#6 Already read that, thank you though