Cylinder head from YFM250 - O-Ring needed?
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  1. #1
    Junior Member Franconian's Avatar
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    Nov 2018

    Cylinder head from YFM250 - O-Ring needed?


    I recently bought a new cylinder head kit for a very good price for a YFM250. It fits perfectly, however the O-Ring (file attachment No. 2) does not fit well. The bulge on the YFM250 head is considerably smaller, if I fit the O-Ring it does not seem to sit properly and I am worried that it will leak. Is the O-Ring absolutely necessary? Maybe the YFM250 has a smaller one?

    Any thoughts, suggestions?
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  2. #2
    Senior Member christddel's Avatar
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    Oct 2010
    The seal is identical to more Yamaha engine...XT225, YFM200/250, TW200..

    If you do not put it, the contact surfaces of the engine parts must be very clean.
    With a new seal and a little sealant...

    Personally , I will disassembly the sleeve of the cylinder to rework the groove the oring in the aluminum block

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