FLHRSI Pops

Discussion in 'Engine, Fuel and Exhaust' started by dodomrkc, May 21, 2007.

  1. dodomrkc

    dodomrkc Member

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    Hello all,
    I have a 2004 FLHRSI, recently changed the stock slip on muffs for the Vance & Hines variety. Took it to the dealer for an inspection. He said it was running a "little lean" but not enough for a remap and download. Now when I decel between low gear changes I get a slight to moderate pop. Other wise torque and horsepower seemed to have improved.
    I have always been under the impression that pops come from being too rich, and not too lean. Is that a correct frame of thinking?

    In the mean time, I am considering ordering a set of Big City Thunder baffles to richen the mixture back up a little bit and add the extra torque and HP that the manufacturer claims. Has any one used these and what are the true effects? The Q&A guy at Big City thunder claims that installing a set of these in the end of the head pipes will give the efi a proper read again, which is also my thoughts as well. Just would like some more info before I drill my head pipes to accept the set screws to accept the new baffles.
    Do I sound baffled?
     
  2. Fearless1

    Fearless1 Active Member

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    My 99 flhri does the same thing sometimes in the right conditions and it runs lean to. I got oversized cams stage1 screaming eagle upgrade and vance and hines longshot duals and a remap for the whole upgrade. But it only does it under decelleration when hot and running hard sometimes if I let go totally on the throttle other than that it runs like a rapped ape.
     
  3. dodomrkc

    dodomrkc Member

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    Got the baffles in and everything runs and sounds great. Eliminated the lean pops and has enough torque to pull a tree stump.:D
     
  4. glider

    glider Veteran Member

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    The decel pops are usually caused by the fuel loading up in a hot muffler and not so much the tuning fuel curve of the engine itself.
    If you notice on a decel of a FI harley that you get a lurch in the bike as you decel with closed throttle that is noticable. That's due to the fuel map shutting off the injectors as you decelerate and at about 10-15 MPH they come back on again and you may get a pop depending on how much back pressure you have in your exhaust system. The less back pressure you have the more the pop.
    This can be tuned out using the screamin eagle race tuner as it rewrites the map parameters and does not piggyback the ECM like other units do.
     
  5. dodomrkc

    dodomrkc Member

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    Thanks for the info Glider. Must say that is a really nice Classic you have pictured there. The baffles from the Big City Thunder folks really helped the situation and the pops are virtually gone, with the increase of the added torque, she purrs like a kitten. Maybe you know something about this, the folks at BCT, also replied that I can now either completely remove the baffles in the slip ons or cut them down to further "customize" the sound, what are the pros or cons to doing this?
     
  6. glider

    glider Veteran Member

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    To be truthfully, I wouldn't cut the baffles down any. The BCT baffles do a good job of lowering back pressure in the exhaust and also give you some more sound to boot. By cutting the baffles, you do change the sound but keep in mind that the FI bikes need back pressure to operate properly and perform good. If you go over the threshold where the back pressure is not sufficient, then you loose low end torque and that you can feel in the seat of your pants when you take off. I would leave the BCT baffles as is and not ruin a good thing.

    Thanks for the comment on the classic. I like it a lot and think it's one of harleys best sellers.
     
  7. dodomrkc

    dodomrkc Member

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    I was kind of the same thinking, did not want to ruin something that was already working. Thanks for the input though. Keep the shiny side up.
     
  8. glider

    glider Veteran Member

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    Don't forget now that a leak in the joint at the muffler to pipe or gasket at the head on the exhaust will also cause popping too.