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Thread: R90/6 Base Gaskets

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  1. #1
    Macrunch MCrenshaw's Avatar
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    R90/6 Base Gaskets

    While cleaning the bike yesterday I noticed some oil misting around the base gaskets. Is this an indication that the heads may need to be retorqued? I probably have about 300 miles on the bikes since the last valve adjustment.

  2. #2
    Administrator 20774's Avatar
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    Unless the torque was down around 15 ft-lbs, I wouldn't think that would be of any consequences. Certainly, the torques need to be more or less correct, but I wouldn't get torque-wrench-happy on doing it every time you check the valves. Typically, once everything is bedded in, it's unlikely you need to check torques all that often unless something changes.

    Remember that the explosions in the combustion chamber is literally trying to blow the heads off the the cylinders, pulling on the head bolts, and possibly very minutely, lifting the cylinder off the base.

    I would think you're slight misting is just due to age and/or an imperfect seal that last time the cylinder was off. How many miles since this was done?

    I'd be inclined to say "they all do that" but some bikes can be made such that the oil stays on the inside.
    Kurt -- Forum Administrator ---> 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 donbmw's Avatar
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    Look at you push rod seals and the oil press switch. Could also be head gasket leaking around the push rod opening. I have all the above over the last few years on my R90/6.
    1975 R90/6, 1980 and 1982 R65, !959 TR3A Triumph Car

  4. #4
    Macrunch MCrenshaw's Avatar
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    Oil pressure switch and pushrod seals were replaced about 1,000 miles back. No leaks there. And there are no puddles or oil drips on the underside, only the misting.

  5. #5
    Administrator 20774's Avatar
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    What was your procedures for sealing the base after the new seals were put on and how have you been checking head bolt torque during the 1000 miles?
    Kurt -- Forum Administrator ---> 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
    Macrunch MCrenshaw's Avatar
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    The pushrod seals were done by a factory trained BMW mechanic. I can't say how he installed the base gaskets but the quality of his work has always been top notch. I don't think it will hurt anything to go back and torque the heads. These old bikes need the TLC and it isn't difficult. Just need to be careful to know the correct torque settings, back them off, then don't over torque so as not to damage the threads in the aluminum crank case.

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