250 Supersport piston orientation
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Thread: 250 Supersport piston orientation

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    250 Supersport piston orientation

    Getting ready to install a new piston in my Super sport. The piston is a Mondial 1966 which matches the old piston but I am not sure if it matters which way it goes in terms of top or bottom as there is no obvious mark? Please advise.

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    Senior Member DenH's Avatar
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    hi at is that a 4stroke or two stroke ?

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    Four stroke

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    Senior Member DenH's Avatar
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    i know that on a car engine theres usually an arrow to indicate which way to install it,if there is no marking on it i dont think it will matter too much.
    Philoldsmob likes this.
    when i was young i was very indecisive,now im older im not so sure.

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    Yes, there is usually an arrow. If there is nothing, my gut feeling would to be to orientate any stamping like an oversize number towards the front of the bore.

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    Thanks for the feedback... the only mark is a B but it is off to the side (not front or back). The valve reliefs are identical and by all my measures it is symmetrical so I am fairly confident at this point that it can go in either way.

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    Your observation that the piston is 100% symmetrical is correct, So this piston can be fitted either way.
    Last edited by Peter R; 01-14-2016 at 07:25 AM. Reason: typo
    Philoldsmob likes this.

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    Thanks Peter... now to get it fitted into the cylinder with that troublesome oil ring below the wrist/gudgeon pin!

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