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What's causing the backfiring? I don't have exhause leaks, (ScreaM'N eAGLE pERFORMANCE MUFFLERS). How do you stop the backfiring?h
 

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Jay Mack, there are quite a few prior threads on this, try searching popping, backfire(ing) as a start. Mostly seems to affect efi bikes (assume yours is?).
 

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When you first got your bike, obviously it was installed with factory restrictive mufflers. Your bike was trying to breath, and it couldn't... But you had no popping, or backfiring. Now, I assume you have rejetted, put atleast a stage 1 system on your bike and opened the air flow considerably with SE mufflers.

Now your getting popping / backfiring on decelleration. correct?:confused:

Welcome to the club... A certain amount of popping is normal, backfiring is not. If popping is all you have you can tweek the jets to get rid of some of it, but I doubt you'd get rid of all.
 

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Discussion Starter #5
I guess its more like popping than explosive backfiring. I have a carbed bike. It's a 180 main jet from dynojet kit, though im putting in a 185 tomorrow. So it's not going away? I'm surprised if its not correctable.
 

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Hey Jay Mack,

Unless the thing is backfiring in the upper RPM range(2500 & up)I doubt you'll make a difference with a main jet change. Although a 185 main shouldn't be too awfully rich for a Twin Cam with AC & exh. upgrades, the slow jet and idle mixture may be what you need to look at. Does it fart through the carb when you blip the throttle between downshifts?

Carb farts are not normal! You need to dial that carb in man. You've got an idle or low speed circuit lean condition by the sounds of things.
 

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If it pops thru pipes on heavy deceleration I'm told it is cold air getting past the exhaust gasket. Will not hurt anything. I almost tuned all mine out with idle mixture screw. I got this info from John (Rolling Thunder) at Biketoberfest.
PS Bike, 2002 Flstc Screaming Eagle ignition and Air cleaner, Dyno jet and slide with Python w/powerchamber. 76 hp 84 tq. John said "Good Pipe"
 

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This is what Power Commander told me when I emailed them about my Ultra. I'm running a 95" 2000 stage 1 with wild pigs now. It had SE touring before. After I put the PC on and the right map in the PC it got rid of most of the popping. The only way your going to get rid of all of it is put quiet mufflers back on so you don't hear it.

The right muffler turns blue from excessive heat, the heat is caused by the fresh air being pulled in from the left side. The left side sucks in the air and the air increases the heat of the exhaust gas. It then all goes out the right side. If you block off the left side, remove muffler and stick a freeze plug in, the reinstall muffler, this will stop the air from being pulled in. This will reduce the temps and also reduce the decell popping. With high flow mufflers all the exhaust goes out the right side anyways so it will not change the performance.
 

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a properly tuned motor does not pop, I had Hooker slip-ons that did not pop once the PC was tuned, I have a pro-pipe that does not pop, I have had screamin eagles that did not pop...........
 

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Guess by the sound of it your one in a million then, all my bikes have had some pop on decell. And just about everyone else has too. But what the he11 do I know I've only been riding since 1969 :D
But then again it depends on what you consider a pop.
I'm not talking rifle shots, just a rummble thats not totaly even.
 

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I agree, and most I think would also... After changing to after market pipes EVERYONE will experience some popping of some kind. I don't care how much you tweek you mixture, and jets, you'll never get rid of it completely.

Pop, popop Pop on decell is normal.
 

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Nope! Self modified Kehin on a hi-comp 95" TC w/hot heads, cams and ign. Smooth as a cat on the throttle & off. 2500 miles and nary a carb fart or exhaust pop. Must be two in a million!
 

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Just my .02. . .
Have to join the "a bit of popping on decel is normal. (and KNOW that some DON'T) Mine's (carb)ega/dyno setup, and has always done it (always had slip on free flows (Kerker) and stage 1 a/c).
Did observe during a trip out west, that my left pipe, which had alway been fairly cool, burned me when I relaxed my hand down by the seat during a trip out west, extended high speed riding. From that, think the left does get used during the higher speed runs, just not much for all the "normal" urban/suburban type riding??
Rode a loaner FI Heritage not too long back with SE stage 1 pipes - it had no popping, but then, for some reason, (I hear it's not normal) the bike had no decel. Somehow, the FI only let it back off very slowly. LOL - no decel, no popping.
Good rides,
RainRider '02 FLHT
 

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Not sure why some have concluded that "some popping is normal." That would drive me nuts! I have a FLSTCI with Stage I air cleaner and V&H Pro Pipe HS's with a remap. I have absolutely no popping. I only mention that because I don't understand why popping should be considered normal or acceptable. I should say that I have no mods other than those and am very happy with the power, sound and performance. I guess I would rather have a bike with this set-up that runs smooth as honey than a heavily modified bike that can beat a sporty off the line at the light but sounds like crap. To me there is nothing impressive about a poorly tuned bike no matter how much horsepower/torque it has or how loud it is. By "tuned' I mean the appropriate selection of engine/exhaust accessories as a package--not just some of this and some of that. Hope this makes some sense. It's just that a lot of my pleasure enjoying machines is what they sound like and how they perform. Just for comparison I seem to have lots of decel (if you mean compression) and rely on it regularly for slowing prior to curves rather than braking.
 

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Good to know that the norm for FI is to have compression decelleration. I'm riding a loaner/rental '03 FI RoadKing right now while mine is in the shop for the 20k service. It also has very poor compression decel. Maybe it's just the way this dealer sets them up??
This one has no popping either, and it has stock air cleaner, but with what look like Sampson (so I'm told) slash up slip-ons - (sounds pretty good).
As far as not understanding why some accept it - different strokes for different folks. I've talked to enough people who know Harleys pretty well, and heard enough to not get excited with a bit of popping, but draw the line at more than a very occassional backfire (may only hear one a week, or less), and don't want to have any carb backfiring at all.
There are several good explanations about why exhaust popping occurs, mostly about fresh air hitting an abnormal mix caused by closing the throttle. I'm not including exhaust leaks as part of it - that would get into the excessive area.
Anyway, I'm ok with mine -
Good rides,
RainRider
 

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Exhaust "poping" can be do to s few different things. A well tuned bike with junk for exhaust could pop all right. A poorly tune bike with quialty exhaust the has a lot of scavaging may pop very little if at all. All the poeaces make it happen or not.

On carb bikes that are tuned for preformance poping from high rpm's is a fact of life.
 

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That's odd... My 95" hi-comp(10.5 to 1), hot cams(.569 lift, 257 comb. dur.), trick heads, hot ign., self modded & tuned carb, has no tendencies to cough, fart, pop or backfire at any RPM, during accelleration no matter how hard, or decelleration. Never has since the build was done over 2,500 miles ago.

A properly sorted out engine whether stock or highly modified should have none of the above mentioned bad manners.
 
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