popping and backfiring on decelleration

[barmstro]

Just cleaned carborators and I suspect I might have air scew set wrong.I found info on this site says 2 turns out.
The PO did 3rd stage dyno kit to carbs ,as well as 4 into 1 and k&n cones.
Will these changes affect that pilot screw setting.The bike accererates
smoothly but pops an is unstable at even speed and moreso at decelleration.

[apogeecustom]

I just colortuned my screw settings. I had popping on decelerating. I did the recommended 2ish turns out before hand. I ended up going way past 2 turns to get the right color. No more popping and now I'm getting 43 mpg. Not sure about your jet setup but the pops are likely from lean mixture.

[posplayr]

Agree sounds Lean. makes me wonder about jets and where the nEedles are set. using an o2 sensor just corrected my jetting . i had too large of a main which caused me to raise the needle in an attempt to lean thenmidnrange. This made my bike run rich at idle with two and half turns. Now lowered the main from 145 to 140 and now needle dropped from 4 and 1/2 from bottom to 3 from bottom and mixture screws are 1.75 turns.
Double check jetting first but soundslike u are lean on mixture screw

[apogeecustom]

Just cleaned carborators and I suspect I might have air scew set wrong.I found info on this site says 2 turns out.
The PO did 3rd stage dyno kit to carbs ,as well as 4 into 1 and k&n cones.
Will these changes affect that pilot screw setting.The bike accererates
smoothly but pops an is unstable at even speed and moreso at decelleration.

Also, you're probably pretty close to the right mixture. You said it's smooth on acceleration. The carbs are designed to rich out during acceleration which is probably why you're not getting the issue on speed up. I don't know your bike model, and I don't know enough about rejetting and pipes so someone can put me in my place, but I would turn your screws out another 2 turns each and see if the problem goes away. Fill up your tank, set your trip to zero, go ride 50 miles, fill up your tank again and see how much gas it took to fill up again. See what kind of mileage you're getting. Otherwise you need to do all that plug chop nonsense