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Thread: found something odd.

  1. #1
    Rally Rat
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    found something odd.

    so I bought a pile of parts from an older gentleman, who was cleaning out a storage.

    it it, I found this...

    According to the serial number, it's a 1974 R90S. But it's got this odd machined flat spot on the outside of the motor, down at the bottom.

    Anyone know what that is?

    20130601_092759.jpg
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  2. #2
    Sir Darby Darryl Cainey's Avatar
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    My 1977 R100RS has it as well.

    My guess it is a locating point for a machining process.
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    1977 R100RS, (Retired) 1993 R100GS (just getting started)

  3. #3
    Administrator 20774's Avatar
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    Snowbum mentions a milled flat area in about the position you show...3 inches by about 1-1/2 inches. He seems to indicate that it was mostly 1983 or so and on, but not 1970s bikes. This area contained information about the production of the engine, but he said it could be blank, too.

    If that's what this is, I wonder why it appears on a 1974 block?
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  4. #4
    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by 20774 View Post

    If that's what this is, I wonder why it appears on a 1974 block?
    Practice???
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
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  5. #5
    Administrator 20774's Avatar
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    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  6. #6
    Registered User lmo1131's Avatar
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    If that's what this is, I wonder why it appears on a 1974 block?
    The same reason my 12/'72 build 1973 R75/5 has the hydraulic steering damper mounting tab on the frame ... per Paul ... practice, just gettin' ready for the next model.

    Is it just me, or do you all see TWO images posted above?
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  7. #7
    Registered User lmo1131's Avatar
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    Just found this on RealOEM in ALL (European and USA) R90S Engine > Engine Running/Gear > Short Engine



    Under the "Engine Block" heading, the boss does not appear.



    This is the previous-life, technical illustrator in me surfacing. These are great old school illustrations ... from different viewing angles no less.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  8. #8
    Administrator 20774's Avatar
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    Fiche diagrams can be notoriously wrong...or general in nature. That said, if what Snowbum said is near correct, that this boss didn't appear until the early 1980s, did it really take BMW 8 years to "practice" that? I can see a few years prior, but that seems a bit much.

    And I see two pictures...of the same thing.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  9. #9
    Registered User lmo1131's Avatar
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    ebay

    '74 R90S

    serial number 4930124 ... nice breather mod, eh?


    1978 R80




    '83 R100



    edit - almost looks like it was intended to be part of the lubrication system... (?)

    kinda curious how a double image post occurred. but just curious.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  10. #10
    Rally Rat
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    I must have flubbed the picture posting, sorry.

    so, I'm thinking it's a replacement short block?

  11. #11
    Administrator 20774's Avatar
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    My '78 R100/7 block...there's too much inconsistency here...there must be some other variable not being considered. European vs Rest of the World?
    Attached Images Attached Images
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  12. #12
    Registered User toooldtocare's Avatar
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    I looked at some photos of my old 74, R90S and it does not have the boss. Wonder why?

  13. #13
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    Some countries in Europe (Germany is one) require the engine serial number to be included in the title. When you take your vehicle to the mandatory technical inspection (T?V) every two years, they check the engine number. This is why it has to be in a halfway accessible spot. Therefore, some motorcycle manufacturers moved the engine serial number from an original (hidden) place to another spot where it could be seen. Maybe that is what you have here. A block that was intended for use in one of these countries.

  14. #14
    Registered User lmo1131's Avatar
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    could be. but there isn't anything much easier to find on an airhead than it's engine number.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  15. #15
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    checked mine, the 1406th off the line in Nov. 1973, no auxiliary numbering plate on lower left side of block. Numbers easily read standing up by oil filler and right upper frame gusset.

    could be wrong, but that lower left block info spot showed up after '77?

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