Square or round exhaust port?

Discussion in 'High Performance Bicycle Engine Tips and Motorized' started by DRK, May 19, 2017.

  1. DRK

    DRK Member

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    Which cylinder is best for performance on a stock 66cc CG motor and why? Trying to learn.
     
    #1 DRK, May 19, 2017
    Last edited: May 19, 2017
  2. Dan

    Dan Staff
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    If I am understanding your question correctly, DRK. I don't personally think one has an advantage over the other, other than the more fin, surface area, the better cooling capabilities.

    Other than that, I don't think aside from aesthetics, one is any better or worse.

    I'm looking forward to seeing what other folks think, though.
    Just my 27 cents. (inflation)
     
  3. MotorBicycleRacing

    MotorBicycleRacing Active Member

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    Square or round exhaust port?

    OP didn't ask about the cylinder shape.

    The shape of the exhaust port which you obviously can't see when the
    exhaust is bolted on the cylinder.

    Round should theoretically be better but on these motors there are too
    many variables to consider.

    That's my 2 centavo's
     
  4. mobike91

    mobike91 Member

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    I'm thinking that the round shape would allow for more sound wave from a pipe to more effectively push the scavenge of the fuel mix back into the cylinder. Can't prove it, but in my mind it seems logical. Guess I'll have to build both and test ride the snot out of both lol
     
  5. Dan

    Dan Staff
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    I did mis read.

    My muffler and pulse jet guy, "Pops" (Yup, have a pulse jet for MBs, guy) Says that if you think of an engine as a pump. The hot gasses spiraling, can evacuate faster and make turns more easily. Allowing the whole occurrences of events to happen faster.
     

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