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Thread: Idle on a /5

  1. #1

    Idle on a /5

    I have a 1970 R50/5 that I just acquired and the idle is very slow. Can someone let me know how to increase the idle speed? I am a vintage Moto Guzzi rebuilder (both me and the Guzzis are vintage), bit I am not familiar with Bing carbs yet... Thanks. Lee Davis

  2. #2
    Liaison 20774's Avatar
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    That should be a Type 53 slide carb and here's an exploded view from the Bing site:

    http://www.bingcarburetor.com/bmw/53.../Type%2053.pdf

    Item #12 is listed as the idle speed screw. I'm not that familiar with these carbs...the CV carbs adjust idle speed with a screw from the bottom.

    Note that idle speed adjustment is part of a full carb sync, which includes idle mix and throttle cable tension. But increasing the idle RPM will certainly help the bike run better at idle. Try to make the same adjustments on each side for starters. Fine tuning will be in the carb synch.
    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
    Registered User m_stock10506's Avatar
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    The large adjustment screw on the side of each carb is the idle speed adjuster.

    R60Carb.JPG
    Michael Stock, Trinity, NC
    R1100RT, R100, R60/6

  4. #4
    Airmarshal-IL James.A's Avatar
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    Be sure to check the valve tappet clearances. If the clearances are tighter than specified, it will adversely affect the idle when the motor is warm and if they are way tight it could affect idle cold as well.
    1973 R75/5

  5. #5
    Liaison 20774's Avatar
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    Very good point, James! . Sometimes engine performance is not always the carbs.
    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!

  6. #6
    Airmarshal-IL James.A's Avatar
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    Right, Kurt.

    The only reason I know this is because I pushed the valve seat recession issue almost all the way to terminal. At the near break point, the valves on my R75/5 would change to where the idle would not hold up in intervals of 500 miles. I damn near run that motor to ruin. Valve recession, in my case, would always display as a super low idle, or motor refusing to idle when coming off highway speed. It seems reasonable that tight valve tappets would affect idle stability at any mileage or operating temperature. It's just another angle to consider. In my experience, there are many factors that might contribute to these symptoms when we are talking about type 53 carbs. largest among these are the O-rings at the top of the ring that holds the mechanical slide in the carb, or the stubs for the intakes where the carb throats and/or the sleeves fix to the heads.
    1973 R75/5

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