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Thread: SuperMeg disc tuning

  1. #1
    Strider Guest

    Default SuperMeg disc tuning

    I have a 2003 Heritage w/ EFI. It has a 95" kit and stage 1 heads from NRHS and an Andrews 37G cam. I didn't know much about setting up the discs on my SuperMeg exhaust when I first put this together so I ordered extra discs and I started with 26 discs and the end cap installed. When I took it to be dynoed the shop said the end cap was hurting performance so they removed it. That is where it is now but from what I have read on this forum I don't think that is right. Other reccomendations seem to indicate that 16-18 discs w/ end cap might be about right. I recently purchased an open end cap and I would like to try using that. Would 9-10 discs with the open end cap seem like a good set up? Any help will be appreciated.

  2. #2
    bschultz Guest

    Default

    The open end cap + 9-10 discs would be a good place to start tuning with you build; however you may need to tweek it by adding/removing 2-3 discs.

  3. #3
    Strider Guest

    Default

    With the current state of tune (26 discs and no end cap) it seems to run rich to me. Plugs are more on the black side than tan or cream. What will changing to 9 or 10 discs and the open end cap do? Is the open end cap the same as no end cap? I am also considering upgrading to a 51mm throttle body and I would like to avoid repeated visits to the dyno.
    Last edited by Strider; 09-08-2011 at 08:43 PM.

  4. #4
    bschultz Guest

    Default

    The pipe has nothing to do with the bike running rich. The discs you have on it are of NO use if your not running an end cap. Without an end cap you are flowing the core which on a 2:1 SuperMeg is 2.5", fed by 1.75" primaries and should be more than enough exhaust flow for your build.
    If it is running rich, the fuel issue needs to addressed before trying to tune with the exhaust flow.

  5. #5
    Strider Guest

    Default

    Thanks. I saw on another thread that if the plugs indicted it was running rich, adding discs would help lean it out. And if it was running lean, removing discs would richen it. I have changed to 10 discs and the open end cap. I took a short ride and it seemed OK. It certainly didn't loose power. The exhaust sound definitely changed. I will ride to work tomorrow and check the plugs when I get home to see if there is any difference. I talked to a local shop (DynoJet Tuning Center) today about getting the map right. He said he was familiar with adjusting the discs on a SuperMeg.

  6. #6
    bschultz Guest

    Default

    Good, the DynoJet tuner sounds like he knows his business.

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