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  1. #1
    seaobin's Avatar
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    Piston Rings --Sizing

    General Question

    How are piston rings sized?

    Do you order by bore size or piston crown size?

    Can you get a little thicker ring to fudge a rehoned cylinder that you dont want to over bore?

    Thanks

    Sean


  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Bore size

    ex. 750 .25mm oversize

    You can try going 1 size up in order to close up the ring gap, but you'll still have excessive piston to cyl clearance.

    How much are we talking?

    If it's that far past spec, you may be able to hone the cyl to the next size up. Then just get a replacement piston kit.

    That way clearances are all good. If you go 1 size up, it shouldn't affect crank balance that much for a rec boat.

  3. #3
    seaobin's Avatar
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    so if my Sl750 that is .5 over already and my compression in mag is 90 psi. if I hone and rering, i use the same size ring, or do i go larger and use the ring to make up the difference.

  4. #4
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    If you're at .5mm now, hone the cyl and see what size it's at.

    If it's out of spec, try to go .75mm on the piston and ring.

    If the piston is within spec, you can install another .5mm ring.

    If it falls somewhere in between, you MAY try to run a .75mm ring with the .5mm piston. Just make sure the ring gap isn't too tight. (absolutely not recommeneded, but may be a cheap fix in a pinch)

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