Airhead Vibration Cured

Discussion in 'Airheads' started by Xcuvator, Feb 21, 2011.

  1. Xcuvator

    Xcuvator Justa Venturer

    Joined:
    Jul 23, 2007
    Oddometer:
    1,374
    Location:
    Skolls Or
    I have posted some questions here regarding my search for a crank for my 76 90S. The bike is one I restored a couple of years ago, but was never happy with the level of vibration in the foot pegs. One of the things I like about the 90 motors is they are almost as smooth as a 75, but this one vibrated as much or more than the 100s I've ridden.
    So finally this winter I tore it back apart to find the crank was out of spec. So the search began for a replacement. I looked at five that for one reason or more felt weren't suitable. One of the most disappointing was from regular seller on IBMW, who turned out to be not only incompetent, but also dishonest.
    So finally I just started emailing people I had had contact with, who might have a lead on one. One such email went to our own Robert the Wirewerker. He said he had one but he would need to take it out and measure it. Measure it? This was something I had not heard from a seller before. So a couple of days later I hear back that it checks out to be very good. By this time I felt like UH HUH, we'll see. But a few days later
    Robert had the crank at my door and to my pleasant surprise I found the rod throws at the upper end of the spec, the mains fell into one of the color codes and they were all very round.
    Yesterday I took the bike out for a test run and found it to be a very smoooth running R90S. Up until then my 74 90S was the smoothest airhead I have ridden, now I'm not so sure.
    Oh, and many thanks to BMW Wrench for all the fitment clearance tips.

    [​IMG]
    #1
  2. Uncle Ernie

    Uncle Ernie Long timer

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    Jul 3, 2007
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    Asheville NC
    Wow- the red paint really faded bad, didn't it.
    Now that it runs good, a quick re-spray and you'll be proud to go out in public again!

    Mazel tov ! >clink<
    #2
  3. Xcuvator

    Xcuvator Justa Venturer

    Joined:
    Jul 23, 2007
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    My cheap Kodak makes my red bike look terrible. My good camera blew out of my not zippered tank bag, sorry for the distress.
    #3
  4. Wirespokes

    Wirespokes Beemerholics Anonymous

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    That's good news dude! So that's why I haven't seen you in forever, right?
    #4
  5. fishkens

    fishkens Long timer

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    Nov 14, 2009
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    Nice!

    Do you have pics of the rebuild that you can post?
    #5
  6. Hawk Medicine

    Hawk Medicine Coyote's Brother

    Joined:
    Jun 8, 2008
    Oddometer:
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    NOR CAL
    Glad you got your bike back together and running right!

    Having sold my share of parts on IBMR and Ebay, I find it astounding how few people ask questions, before shelling out money for used parts. There are also a few things that I wouldn't sell without having someone knowledgeable look em over and a crank is one of them. I can just imagine sending someone a used crank and then having it fail after the buyer completed an expensive rebuild. I wouldn't be able to sleep for a month!

    The other side of the coin is that there are some real asshole buyers out there but thats a different story!

    I think you're pretty lucky to have hooked up with Wireworker. Hes one of the more knowledgeable guys around here, when it comes to parts and the items that I've gotten from him have always been better than I expected and cheaper than I would have otherwise paid.

    Sounds like a good deal all around. Now... Go ride your bike!
    #6
  7. Xcuvator

    Xcuvator Justa Venturer

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    No I didn't take any, didn't think there would be much interest and on top of that, like I said my camera leaves alot to be desired, especially on indoor pictures. I have been punishing myself for loosing a fairly good one.
    #7
  8. Caddy82rats

    Caddy82rats Long timer

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    South France
    interesting I haven't imagine that a crank can act like that for vibration.
    and good looking bike
    #8
  9. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Believe me, it's stunning in person!
    #9
  10. RecycledRS

    RecycledRS Along for the ride

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    Nov 2, 2008
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    Location:
    Vancouver Island
    Just for future reference, what was wrong with the crank?
    #10