Slip on Muffler Question

Discussion in 'Other Service and Maintenance' started by Jack49, Jun 1, 2014.

  1. Jack49

    Jack49 Member

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    I have an 08 Ultra. The mufflers are true duels with stock muffler with a label saying use on 1584 - 1688 cc motors. i got 2 slip on mufflers label saying use on 1340 - 1440 cc motor. I took the 1340 - 1440 cc muffler and cut the rear baffle center plate out with a 1 inch hole saw. I drilled 4- 3/8'' holes in the front baffle. I put his modified muffler on my bike and it sounds real good. It has a real nice growl when I crack the throttle. Here's my question. By removing the rear center plate baffle and drilling 4- 3/8 inch holes in the front baffle of the muffler did I do enough to insure good exhaust flow with minimal back pressure?
    She rode real nice. I did not notice anything trying to slow her down. With summer coming I don't want it to run hotter than normal. What else can I check?
     
  2. Breeze3at

    Breeze3at Well-Known Member

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    You opened them up pretty good. I would be comfortable with running them as now modified.
     
  3. Jack Klarich

    Jack Klarich Expert Member

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    You can get by with a change like that with out TOO much fear, how ever if you change the air in as in air cleaner up grade you will need more fuel, that said these beats run lean from the factory so more fuel is a plus to keep it cool and add power
     
  4. Jack49

    Jack49 Member

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    Hey Guys, Thanks for the quick response. I felt like I did open them up pretty good and man, they do sound nice. The bike is fuel injected so I thought the computer would make the adjustments after I rode it a while. Would it be worth disconnecting the battery for a while to have everything reset itself?
     
  5. gator508

    gator508 Senior Member

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    I don't believe you can hurt anything by disconnecting the battery, however as I understand it, the ECM is a learning type computer and will adjust as you ride, so that may not be necessary.
     
  6. Jack Klarich

    Jack Klarich Expert Member

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    Nope, I would like to meet the guy that started that rumor:p
     
  7. Jack49

    Jack49 Member

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    What rumor are you referring to. The bike being fuel injected and the computer making the adjustments or disconnecting the battery and clearing the memory?
     
  8. Jack Klarich

    Jack Klarich Expert Member

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    Disconnecting the battery to clear the computer. This may work to some degree with OBD 1 and 2 on cars but not on the Harley ECM, the down load wil remain intact, if I had a nickel foe every time I see this I could be rich. All of the modern day ECM have artificial intelligance and are capable of making the right decisions based on the maps and software, do not let any one convince you other wise
     
  9. wazzle

    wazzle Member

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    Not sure about the Harley ECM but automobile ECM's have had adaptive memory for years. Disconnecting the battery clears the adaptive. Ford for example many times won't idle after a battery is disconnected or goes dead. The buildup in the throttle body restricts air past the blade but the ECM has compensated over time. The throttle body has to be cleaned to restore idle. I would wager the Harley also has adaptive memory. Disconnecting the battery won't affect mapping or programming. Just the adaptive.
     
  10. Breeze3at

    Breeze3at Well-Known Member

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    I'm pretty sure Harleys do not have adaptive (learning/compensating) memory in the ECU. Once a code sets it stays disconnecting the battery won't clear it. If the IAC is dirty the bike will keep stalling or idling bad until it is cleaned, the ECM won't learn to idle. The one thing the ECM will compensate is for the very lean air fuel ratio. You can't make it run rich by restricting the intake or exhaust.