oil in compression chamber

Discussion in 'Airheads' started by sakinjp, Sep 29, 2013.

  1. sakinjp

    sakinjp n00b

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    Sep 2, 2013
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    1971 R75/5 bmw I have oil fouling up my spark plug on one side keeping that side from firing. How do i fix this? Its the right side and parked on center stand I believe this engine not orginal has 35000 I rode it with this engine a couple of years before it started acting up. I have never set the valves and don't remember if I have had anyone do it.
    #1
  2. ozmoses

    ozmoses ...

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    Type 247 motor?

    Breather valve working?

    Valve job?
    #2
  3. Kai Ju

    Kai Ju Long timer

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    or as disston would say: Brand, model, mileage ?
    I'm adding brand since I don't know whether this is even a BMW...
    #3
  4. 190e

    190e Long timer

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    Which side is fouling on your R75/5 the left or right?

    Reason for asking is the engine breather on your bike dumps crankcase ventilation vapour into the right hand carb only so if it is the right it might be a breather problem. Could be other things like excess crankcase pressure due to piston blow by or worn valve guides.
    #4
  5. Plaka

    Plaka Brevis illi vita est

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    left side?

    Running the same plugs as always? What plug are you running? (the brand and plug number)

    Doing a lot of short trips?

    Change type/brand of oil recently?

    Miles on the bike?

    Set the valves recently?
    #5
  6. Big Bamboo

    Big Bamboo Aircooled & Sunbaked

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    ...and if the bike was parked on the side stand, oil will sometimes get past the rings on the left side and smoke on start up.
    #6
  7. disston

    disston ShadeTreeExpert

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    If it is not the breather system and the bike is not being parked on the side stand then you are going to have to do a compression or a leak down test.

    A lot of times it is the breather or parking. So, pray tell, what side is being fouled?

    And try to answer some of the other obnoxious questions we ask too. A couple of them at least.
    #7
  8. Jon-Lars

    Jon-Lars Jon-Lars

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    Apr 23, 2006
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    #8