carb

[bud1]

I Am New To Harleys I Have Been Riding For Many Years, Just Bought My First Harley 04 Low Rtder, Love The Bike Just Wandering If There Is Any Cure For The Popping Back Through Carb. I Have Se Slip Ons And Air Box Any Info On Jetting Etc. Would Be Helpful

[HDMD88]

Originally Posted by bud1

I Am New To Harleys I Have Been Riding For Many Years, Just Bought My First Harley 04 Low Rtder, Love The Bike Just Wandering If There Is Any Cure For The Popping Back Through Carb. I Have Se Slip Ons And Air Box Any Info On Jetting Etc. Would Be Helpful

That is called Decell poping and it usually a rich condition in the idle mixture circut of the carb. It could be caused by an exhaust leak also. Did you have a jet kit put in your carb or did some one do you some adjusting along the line after the pipes were installed?
I am partial to a Dynojet kit for the C/V carb but I still put them on the Dyno to tune all the circuts. The kit cost $75.00 and it gives you better throttle responce, and smother transfer through the circuts. The kit doesn't come with a pilot jet, I suggest you get one. You have a 46 in the carb now, get a 48 to start with, that will get rid of any popping through the carb off idle. The directions for the Dynojet kit says to back the mixture screw out 3 turns, but since your changing the pilot jet set the mixture screw at 2 turns out....if it still pops on decell turn the mixture screw in another turn and try it again. If you adjust the mixture screw in futher than 1 turn the pilot jet is too big.
Good Luck

[dfaussone]

My buddy had the same problem on his 03 FXDL. We did eveything - jets, idle jets, leak tests, sealed the exhaust, very frustating. Put on the stock mufflers - no more popping. Our conclusion: it's the slipons. Changed to Thunderheader, no popping and it sounds great. Just my $.02.

David

[11963]

nightrider.com go to tech

[murphdog]

bud1 is asking about popping through the carb, not decel popping through the exhaust. Carb popping is a lean idle/slow mixture (as is exhaust popping/backfiring when closing the throttle). You should be able to cure the carb popping by adjusting the mixture screw out a little to richen it up. Your stock 45 slow jet should be good with just slip ons and air cleaner.
Read the article by Joe Minton here: http://205.214.91.71/forums/showthre...light=27094-88

[ratrider]

Quick question: read that very nice explanation on CV tuning. I am not clear on adjusting the idle mix screw. Did you mean 1/2 - 1 1/2 ADDITIONAL turns out or from full in?

[murphdog]

rat, he (Joe Minton, not me) means 1/2 to 1 1/2 additional from where you find it when you remove the plug. Usually 2 1/2 turns from bottomed out will be close.

[killmeyer000]

i agree with the other posts that say you are running lean. sounds like your bike is breathing better now that you opened up the exhaust and air cleaner. but, when you change the exhaust and air cleaner, you must also make changes to the carb. you might be o.k. to just adjust your mixture screw out a bit (first you have to drill out the mixture screw cover. mixture screw is on the bottom of carb). my best case scenario recommendation is to move up to a 48 slow jet...and back your mixture screw out about 3 turns.

[HDMD88]

Originally Posted by bud1

I Am New To Harleys I Have Been Riding For Many Years, Just Bought My First Harley 04 Low Rtder, Love The Bike Just Wandering If There Is Any Cure For The Popping Back Through Carb. I Have Se Slip Ons And Air Box Any Info On Jetting Etc. Would Be Helpful

Sorry I read the post wrong....popping through the carb is a lean condition, I agree....I just can't read.

[roadhippie]

In some cases backfiring thru the carb is normal on startup, especially if modified pipes/slipons are added.

[murphdog]

Originally Posted by roadhippie

In some cases backfiring thru the carb is normal on startup, especially if modified pipes/slipons are added.

It's only normal if you don't fix the carburetor.

[roadhippie]

Originally Posted by murphdog

It's only normal if you don't fix the carburetor.

Not necessarily. Starting a cold engine does not vaporize fuel completely creating an overly lean mixture, when it does fire the excess fuel is backfired thru the carburetor. Cams w/ late intake valve closing points can cause low rpm backfiring thru the carb. Very open exhaust can cause backfiring thru the carburetor. And incorrect accel. pump adjusment can cause backfiring thru the carburator. Whether it's normal or not is a matter of opinion and depends entirely on what's installed, not necessarily a problem with the carburetor.

[murphdog]

Point taken, hippie. In the original question though, bud1 only said he had SE slip ons and air cleaner..no cam or carb with an adjustable accelerator pump. My experience with a setup like this has been to richen up the idle slightly to get rid of the off idle carb pops. If he has carb pops anywhere else, it's probably not the idle mixture.
But like I've read so many times, "every engine is different" (even though they all come off the same assembly line).

[roadhippie]

Agreed, I'm fairly new adjusting my carb (carbs) and am finding out there are so damn many variables in tuning it's getting difficult to find the right combination sometimes. A good example is over the past couple of weeks I had been getting some major popping out of the exhaust, I was at the point of adjusting the carb again. Instead I replaced the stock HD plugs with a set of Autolite 4164's, the ones some dealers use on the SE builds, I set the gap to .042 and rode the bike about 40 mi last night. The popping decreased 90%, had better acceleration and butt torque seemed improved.
Right now the bike is running lean with the 42 installed but I order a Twin-Tec WEBO and will start with that next next week. (startin to get anal about this)
From what I've been reading I'm convinced there is really no perfect AFR one can set on the tc88's EFI or Carbed. It's the nature of beast. However, it's also the most fun.