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Thread: Cylinder base gasket

  1. #1
    Atomic City Boxer 154048's Avatar
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    Cylinder base gasket

    When I pulled my right cylinder today, I was somewhat surprised that it doesn't seem to have any type of base gasket. (The jug is not machined for the base o ring style, but I had expected to find a base gasket...)

    The bike is a 1980 R100...did they not use base gaskets in certain years or did a previous mechanic just not install one?

    Thanks....

    That right cylinder base has long accumulated a light oil stain where it joins the block...hmmm...I wonder
    Steve in Santa Fe
    1980 R100RT
    2005 DR 650

  2. #2
    Atomic City Boxer 154048's Avatar
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    After doing some reading I find that my bike apparently doesn't have a base gasket. nor is set up for the big O ring...
    (just the two smaller O rings on the two upper studs.)

    Question is do I want to put a very thin film of gasket sealer on the base....

    Probably not. I don't mind cleaning the slight mist stains that appear over time...rather than having to remove gasket sealer the next time I am in there.
    Steve in Santa Fe
    1980 R100RT
    2005 DR 650

  3. #3
    Registered User PAS's Avatar
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    My 81 R100RT does have nikasil cylinders and uses a large O-ring at the base. I still apply a very slight amount of RTV type sealant to the flat surfaces. Did I say VERY SLIGHT!

  4. #4
    James.A
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    I have used the lightest of a skim coat of Hylomar with great results.

  5. #5
    Administrator 20774's Avatar
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    I am getting replacement cylinders from Ted Porter for my R100/7 topend rebuild. The kit contains 9.5:1 compression pistons, too high for me and I'd rather not covert to dual plug ignition at this time. He will be including a compression reduction gasket which knocks it down to 8.8:1. As for sealant, Ted said he puts a thin smear on the engine base, and then another thin smear on the outboard portion of the gasket. He doesn't put any on the base of the cylinder as that will get messy when handling the cylinder for ring installation.
    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
    Registered User PAS's Avatar
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    I believe Ted no longer uses the Hylomar. What did he recommend?

  7. #7
    Administrator 20774's Avatar
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    Quote Originally Posted by PAS View Post
    I believe Ted no longer uses the Hylomar. What did he recommend?
    His sealant of choice is Permatex Ultra Gray...at least he didn't offer anything else when I suggested it in my email to him.
    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!

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