Backfire Issue

[nswsparky]

I have an '07 Phazer with a GYTR muffler, which is just a Skinz Ultra Q. I am having an issue with it backfiring. After I close the throttle a couple seconds later it will pop, loud. And the faster I rod on it the louder it bangs when I let off. It does it just about every time.
Its been doing it for a couple years now but it seems to be getting worse. Since it started doing it, I installed a cold start computer, and new de-comp spring. (It did it before I put this in)
Today I opened it up and put in new plugs and checked all the exhaust parts, no leaks or soot. The plugs where not burnt up or anything, like its running lean. They had a bit of carbon build up, but not bad. I just had the intake apart this past fall and did not notice any missing parts or holes.

Any other ideas? could I have a valve leaking by?

Here is a vid I made up it does it twice you can hear the pop and see the blue flame out the exaust. It is alot louder than the video makes it out to be the camera muffles the sound.

 

[ATV PRO #11]

http://www.ty4stroke.com/threads/small-pop-backfire-with-header-and-exhaust.139680/ Here's a great read from couple of the site top tech guys.

 

[Voda2000]

My original Ultra Q split along the bottom and it was louder because of that. Might want to check.

 

[MikeWalters]

its a fuel issue, or rather an air to fuel ratio isse

For a short blast take your air box lid OFF and see if it gets worse or better

 

[nswsparky]

Is there anything I can do about an air fuel problem? There is pretty much no adjustment to the fuel ratio with the EFI unless I get like a Power Commander for like $400