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Thread: A question for the collective group- '78R100rs

  1. #31
    Registered User STEVENRANKIN's Avatar
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    I attended it, it was great! St.

  2. #32
    #13338 PGlaves's Avatar
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    The 1977 engines were among BMW's best Airhead engines and the 1978 engines were among the worst because of the combustion chamber changes made to try to meet the new exhaust emission standards. Or so Oak Okleshen wrote more than once.
    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
    http://web.bigbend.net/~glaves/

  3. #33
    Focused kbasa's Avatar
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    '77 R100S and R100RS were the most powerful airhead motors ever offered, fyi.

    Havana Gold for an R100RS of that vintage is the rare color. Most I've seen and most sold were in that lighter blue with the coordinating wheel pin striping.
    Dave Swider
    Marin County, CA

    Some bikes. Some with motors, some without.

  4. #34
    Liaison 20774's Avatar
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    Quote Originally Posted by PGlaves View Post
    The 1977 engines were among BMW's best Airhead engines and the 1978 engines were among the worst because of the combustion chamber changes made to try to meet the new exhaust emission standards. Or so Oak Okleshen wrote more than once.
    It's been a while since I ran across Oak's discussions...maybe Snowbum has it on his website. But it's been my understanding that the serious EPA requirements didn't kick in until Jan 1, 1978. One change that was to be made was changing the static timing from 6 to 9 degrees BTDC IIRC. So, there might be a small number of '78 models built between September thru December 1977 that might still have things in common with the '77 models.

    I did a top end on my 9/77 build R100/7 but don't really know what to judge in terms of changes. There was a squish band that was eliminated along the way. I substituted Siebenrock pistons but kept the stock combustion chamber. The hemi-head shape doesn't go all the way to the edge of the cylinder wall but flattens out before it hits the wall...I wonder if that was the squish band area.
    Kurt -- Forum Liaison ---> 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!

  5. #35
    #13338 PGlaves's Avatar
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    Quote Originally Posted by 20774 View Post
    The hemi-head shape doesn't go all the way to the edge of the cylinder wall but flattens out before it hits the wall...I wonder if that was the squish band area.
    Yes, it was.
    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
    http://web.bigbend.net/~glaves/

  6. #36
    Quote Originally Posted by PGlaves View Post
    Yes, it was.
    Wife wife wife how many remember the honda tv comercial from the 80's when I shifted into 5th I forgot all about her, or when sex was safe and motorcycles were dangerous

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