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Thread: True dual tuning

  1. #1
    dwyerflyer Guest

    Default True dual tuning

    I have an 07 Ultra with true duals. Will the difference in header pipe length affect the number of discs I should use in each side? Motor has 251 cams and mild head porting.

  2. #2
    bschultz Guest

    Default

    Our R&D Department testing shows not enough to make a difference. Rear pipe has tighter bends which makes up for the length difference.
    Last edited by bschultz; 01-03-2011 at 03:32 PM. Reason: add

  3. #3
    Join Date
    Jul 2019
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    Bradford ON., Canada
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    Default

    I was wondering the same thing as on my 2007 FXDL with Harley SE slip on's the rear muffler feels to be less flow out of it then the front one. The flow from the front one feels to be stronger. I just got your slip on,s for my 2007 and will install today or on the week-end. Can I run say one more disc on the one with the lesser flow, the rear one to balance them out and at the same time might help the hot rear cylinder to run cooler as the rear is always the hotter of the two on any Harley???? I know the best way would to have a meter to measure the back pressure of each, which would be the best way to know for sure if they are balanced and at the best back pressure of I believe 2-3 lbs at stated out here. Thanks and have a great week-end all and ride safe eh.
    Last edited by FXDL; 06-08-2012 at 12:15 PM.

  4. #4
    bschultz Guest

    Default

    Experimenting with different disc combinations could prove beneficial or not. More discs usually results in more flow and running leaner.
    Air cooled V-Twins run a hotter rear cylinder simply by design.

  5. #5
    Join Date
    Jul 2019
    Location
    Bradford ON., Canada
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    Default

    bschultz You say running more discs will make the bike run leaner, is that also true for fuel injection as I now it will on a carb fueled bike? Mine is fuel injected. Thanks now eh.

  6. #6
    bschultz Guest

    Default

    Yes, on "open loop" FI equipped bikes prior '07 ('06 Dyna's).

    If your o2 sensors are operating as intended the ECM will make the adjustments to keep the A/F ratio within specs set at the factory.

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