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Thread: cold blooded R80RT

  1. #1
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    Question cold blooded R80RT

    I have a 1982 R100RT, 1982 R100RS, and 1984 R80RT. All 3 have stock jetting. Why is the R80 so much more cold blooded than the other 2? Is it the smaller 32mm carbs breathe poorly? Thicker cylinder walls take longer to heat up? Or ?

  2. #2
    jimmy armour
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    r80 jetting

    hi, I believe the r80 had a few jetting changes,I will try to get more info for you, perhaps some one else may have the answer ,JIMMY

  3. #3
    jimmy armour
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    hello again

    checked Andy Schwietzer,s boxer book, your 1984 r80 should have 32mm,145 main,45 idle, 264 needle jet, with needle position 4, no mention of needle number, are your jets these sizes?, if you wish to try something different,you could take the needle jets from the r100,266 and drop the needle one notch,and see what happens, I ran my 1977 r100s with 2.64 needle jets ,back in the day,hard to warm up ,but good in the mountains, pa and w virgina, which used to be our play ground back then , and change back to go home to flat Ontario,hope this helps ,perhaps someone else may help,jimmy

  4. #4
    Registered User lkchris's Avatar
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    Cold blooded means you leave enricheners on longer?

    Would like to let it idle for a minute to warm up but it won't keep running?

    Cold blooded is not a description of what happens.

    Check for vacuum leaks. Rubber carb mounts/manifolds especially.

    Just know that Airheads don't have fast idle cams nor idle control valves and the extra throttle REQUIRED when running on the enricheners is provided by you. Won't really run without your input. Throttle screw/cruise control screw is handy for this.

    R80s IIRC were factory set up a little rich in this period, but if your jetting isn't factory there's no telling except that that's a mistake.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  5. #5
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    By cold-blooded, I mean it is stumbly. Half enrich after a minute or 3 it still wants to die. Once warm, after a few minutes of careful-throttle riding, it is fine.

    The R100's, even below freezing, only want a minute or two of any enrichener.

  6. #6
    jimmy armour
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    jetting

    Hi again looks like the r80 had a reduction in main jet and needle jet change 2.66 and needle in position 3 ,did you check your jets yet ? hope this assists Jimmy

  7. #7
    Registered User lkchris's Avatar
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    Assuming valves adjusted and jets per BMW, I vote again for vacuum leaks. Enricheners must work, of course, meaning assembled correctly, gasket effective, tube to float bowl able to draw fuel.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

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