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Rejetting issues

Discussion in 'Motorcycle Tech Talk' started by Motorhead1973, May 2, 2011.

  1. JohnnyBiker

    JohnnyBiker Well-Known Member

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    Wow, that is really interesting because I basically have a big sucker, I have a fairly potent 1250 set up, and stock intake as well. hmmmmm wonder why I didn't have the trouble. Could it be because of the cams that are in it???
  2. Lucifer

    Lucifer Well-Known Member

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    JB aren't you using a Spike breather with a long runner on it like a SE heavy Breather??
  3. Motorhead1973

    Motorhead1973 New Member

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    That's what I was thinking. When you throw the whole mix with cam lift duration etc. etc. Just gonna wait for the 1250 kit & some bitch'n cams. Bike is running better than before. Needed a rejetting anyway coming from a mile up in elelvation to sea level. I'm looking at this as building knowledge by trail and error. Thanks for all the input.:D
  4. JohnnyBiker

    JohnnyBiker Well-Known Member

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    Yes, I have the set up from D&M Custom Cycles. Earlier in this thread you said that these set ups run better with the v-ductor in it. I am not convinced of that just yet. I tried it and I thought it really did nothing other than when I was in the cams, however, I do want to put it back in now that I have my exhaust leak taken care of.
  5. Lucifer

    Lucifer Well-Known Member

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    That was just an observation on my part by looking at the shape of the backing plate on the Big Sucker and newer SE breathers compared to the old SE breather that's on my Heritage and the length of the runner on your breather.
    The V-Ductor lengthens the intake track on the Big Sucker and SE and straightens air flow helping the intake wave pulse,my old SE breather has an adapter ring on it which would lengthen the track by about 3/4" and straighten air flow a little . These new ones just blend in to the mouth of the intake having as short a runner as possible and nothing to straighten air flow, which adding the V-Ductor aids it in both respects.
    Your intake runner is a lot longer with your set up and is probably getting a stronger wave pulse and the V-Ductor has less of an effect on it because of the length of your intake track.
    This is just an observation based on my very limited knowledge of the venturi effect and Bernoulli's Principle which Ken would know a hell of a lot more about and way better to explain it than I could,especially since he invented it and it has shown positive results for just about all that have used it.
  6. JohnnyBiker

    JohnnyBiker Well-Known Member

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    No worries friend. I found a pretty good article on Wiki that I thought explained airflow dynamics well. I will PM it to you. Fuel stand off is nasty thing isn't it?

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