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Thread: R27 Carb Problem

  1. #1

    R27 Carb Problem

    Just Had Carb Cleaned And A New Set Of Gaskets Installed. Runs Great Until It Gets Warm Then Runs Real Fast At Idle For 20, 30 Seconds Or Longer. Any Thoughts On This?


  2. #2
    Liaison 20774's Avatar
    Join Date
    Sep 2005
    San Antonio, TX
    There is another forum for vintage bikes, if this is really about an R27 single cylinder BMW...this might be best answered there.

    But, in general, all carbs should be adjusted when they are warm, after a 15-20 minute ride.

    What type of R27 carb? Is the carb number 1/26/xx where xx is 68, 79, 83, or 93? The internal settings are mostly the same except the main jet on the 83 is a little smaller, the main jet on the 93 is a little bigger, and the needle clip position on the 68 is the 3rd position. The idle mixture setting should be two turns out from lightly seated. After the warm up ride, you'll need to adjust the mixture for best idle. You might also need to adjust the idle speed RPM setting.
    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!

  3. #3
    My thoughts are this; Your slide is sticking, or your return spring is weak, or your carb is a piece of ****, or any combination of the three. Right now, I am mocking up a 1/26/114 Bing from an R50/5 to be fitted to my R27. The original carb is the most terrible device I've ever seen. If you want to know the whole story, send me a PM or call 1-309-444-8559.

  4. #4
    Did you adjust the valves on the tight side?
    If so, loosen them up.

    The above might be true if the slide is not sticking and the cable has play at rest.

  5. #5
    Cannonball Rider #52 darrylri's Avatar
    Join Date
    Oct 2003
    Surf City, USA (Santa Cruz, CA)

    Moved to the vintage forum

    You may get a better response here.

    I don't know much about the singles, but if this were a twin, it would sound like a sticking centrifugal advance unit, that needs cleaning and lubricating.
    --Darryl Richman, forum liaison

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