Exhaust Popping/Backfiring on Decel

[PHATASS]

Anyone see a problem with my set-up below? Tuned the carb today and still had to turn the Accelerator Pump Adjustment screw out 4 turns to get a crisp throttle response. Anything lower popped through the carb and hesitated. Also have terrible popping and backfiring out exhaust on decel. Figured these were both signs of a lean condition and was going to up the intermediate to .034 but thought this would be too rich compared to what others are running. Any suggestions?

2007 K9
80 Main
33 Intermediate
Air/Fuel 1.5 Out
Idle 1000 Rpm
S&S Twin Induction Intake
XXX G Carb
Stainless Creations Chaos II Exhaust
Big City Thunder Baffles
Elevation 5 Ft Above Sea Level

 

[chacha]

What kind of baffles you running?

Someone with an 07 chime in -- didn't they have intake restriction plates?

 

[justftw]

My 'o6 did the same thing after I installed homemade pipes on her. A good friend and a good wrench told me to back the enrichner screw out till the motor started to falter. Then screw it back in 1/4 turn. It worked for me. I run a .031 intermediate jet in winter and run a .032 in summer.
I know I'll catch a bunch of shit for saying that, but like it or not, it worked. Give it a try, wadda ya got to lose?

 

[lee]

although popping out the exhaust may point to a lean condition it doesn't necessarily. could be tuned great and still get that. Obvious thing to check is an intake leak and then look at your plugs. if both these check out then may just have to put with it with that specific pipe.

justftw - seems odd that works - you would ordinarily expect a bigger jet in winter than in summer. I guess if it works then it works but seems very counter intuitive

 

[MARV]

your sucking air

either from no backpressure or an exhaust leak IMO

 

[BigDogBro1]

If you are running short pipes and minimum baffles, not much will elliminate the problem due to lack of exhaust backpressure and minimum pipe volume. Barring exhaust or intake leaks and lean carb mixtures. A richer mixture will help to reduce it though.

 

[RRRUFF]

What kind of baffles you running?

Someone with an 07 chime in -- didn't they have intake restriction plates?

I thought the 05s and maybe some early 06s where the only ones with restristor plates. That's when BD was trying the EPA thing.

 

[PHATASS]

My 'o6 did the same thing after I installed homemade pipes on her. A good friend and a good wrench told me to back the enrichner screw out till the motor started to falter. Then screw it back in 1/4 turn. It worked for me. I run a .031 intermediate jet in winter and run a .032 in summer.
I know I'll catch a bunch of shit for saying that, but like it or not, it worked. Give it a try, wadda ya got to lose?

Just talked to Bob from XXX and he pretty much said the same thing. He recommended turning the accelerator pump screw almost all the way out until only 1 thread is grabbing and against all odds, lean out the intermediate to either .032 or .031.