Inside An Airhead Muffler

Discussion in 'Airheads' started by wirewrkr, Mar 13, 2010.

  1. walkingbear

    walkingbear Lets Play Chicken!

    Joined:
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    3,999
    Location:
    Scottsdale AZ..
    couldn't resist....... I even bid on another set.. but got beaten
    out by some guy in California.
    #21
  2. rufusswan

    rufusswan Been here awhile

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    Branson MO
    Interesting. Looks kinda lilke a cutaway of a Bose speaker. Exhaust 'tuning' is a bit of a black art, and the math is beyond me.:pope

    I do know that for each spark of the plug, there are two pressure waves exiting. One is the expanding gas, and the other is pure sound pressure, both of which move at two distinct speeds. Both of which utilize the available 'space' in different manners.
    #22
  3. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Don't forget the waves reflected from the end of the system returning as well!
    #23
  4. Grinnin

    Grinnin Forever N00b

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    I've been looking at cutaways of mufflers wherever I can find them.

    I cannot quite tell the shape of the exhaust path from the front to the back. Is that a simple round tube with another sheet of steel behind it or is it a crecent-shaped tube?

    THANKS for the pic.
    #24
  5. Beemerboff

    Beemerboff Long timer

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    Snowbum suggests drilling 4 holes in the flat portion right at the rear adjacent to the outlet.

    Looking at the slice that would appear to give some gas a straightish path out.

    Probably wouldnt free as much gas as a 1/2 inch hole in the main baffle, but it is easier to reverse if it dont work out as planned.
    #25
  6. JimX

    JimX .. .

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    Mar 4, 2004
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    768
    Was the muffler bearing already gone when you cut it open?
    #26
  7. wirewrkr

    wirewrkr the thread-killer

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    Yeah, they're the first thing to rust out on these models.
    The older bikes had a problem with worn phinifler pins and piston pull-back springs weakening, but these later bikes only suffered from rotting muffler bearings.
    Go-figure.
    RVV
    #27
  8. bmwrench

    bmwrench Long timer

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    Nov 10, 2006
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    3,444
    I just hate seeing part names being used incorrectly It's kannidling pins and piston return springs. A weak piston return spring can lead to many hard-to-diagnose problems, including glowing generator warning lights at engine speeds above 13,000 RPM. A green bulb can improve the symptom, but does not fix the problem.
    #28
  9. wirewrkr

    wirewrkr the thread-killer

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    You Yankees just have a different dialect than Jersey boyz.
    Just remember, Ya canna get thayuh from heyah.
    AHYUH.

    RV
    #29
  10. charliemik

    charliemik Been here awhile

    Joined:
    Aug 30, 2007
    Oddometer:
    420
    Location:
    Flagstaff AZ
    My first Beemer was an R60/6 that had this modification. It definitely had a more authoritative sound than other airhead bikes I'd ride with.
    #30
  11. Grider Pirate

    Grider Pirate Long timer

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    :rofl
    Great. Snot on my monitor.. lovely.
    #31
  12. Max Headroom

    Max Headroom lost in the '70s

    Joined:
    Feb 19, 2008
    Oddometer:
    525
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    New Zealand
    I've seen weak piston return springs unfairly blamed for causing problems when often it's due to incorrectly adjusted fledel valves.
    #32