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Thread: Piston size

  1. #1
    Canadian POWERHOUSE CanadianGPR's Avatar
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    Piston size

    I know it has been posted before, but I can't find it. Where on the cylinder is the size stamping? I want to replace my pistons before one goes. My engine just turned 100hrs today and I want to be safer than sorry. Rather do it now than during the summer.
    Rich.
    Last edited by CanadianGPR; 02-10-2007 at 11:24 PM.


  2. #2
    mrbtd's Avatar
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    Is compression ok ? On a stock ski 100 hours is not that much

  3. #3
    Canadian POWERHOUSE CanadianGPR's Avatar
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    The compression is fine, I'm running a 160lbs head and would rather replace cheap pistons now than take out a cylinder and have to repair it, it's not that cheap up here on the west coast of Canada. And I would rather do it now when I ride only once a week, then do it during the summer when I ride 3-4 times a week. I know 100hrs isn't too much but I ride hard and full out most of the time and lots of tugboat wake jumping. My stock gp800 took out a cylinder at 90hrs.

  4. #4
    philip_gpr's Avatar
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    Rich instead of just buying new pistons you might consider doing what I did to my stock ski.

    Sell off your 1200 cylinders and pistons - you can sell a matching cylinder/piston set for $200 to $300 each. Your high compression head is worth another $200.

    Then install a BB top end. Anything from a 1300 to a 1390 (or larger). On my ski I put on stock 1300 cylinders with a Riva head. You wouldn't believe the difference.

    http://rivaforums.com/eve/forums?a=t...093#2571066093

    I have a couple extra top ends (including a new 87 mm set-up sitting on the shelf at Lowell's) that I would sell if this idea is of any interest. [email protected]

  5. #5
    philip_gpr's Avatar
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    the cylider size is the number that is stamped on the cylinder - look for a number from 0 to 20 - top of cylinder on the exhaust port side

  6. #6
    Canadian POWERHOUSE CanadianGPR's Avatar
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    Thanks Phil.

  7. #7
    Me Hahn and Joe H204YOU's Avatar
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    If you dont go phillips route I would suggest buying all three pistons the largest available(I think c is the largest)and have your cyls. diamond honed to fit.Then your the same on all three with a like new fit.Hope this helps.

  8. #8
    philip_gpr's Avatar
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    OK, I am curious

    How thick is the nicasil?

    How can you tell if a used cylinder has enough plating left or if it is worn down too thin?

    I would think there is a limit on how much you can hone off?

    Is it possible to measure this this or tell by looking at a cylinder?

  9. #9
    WATER WOODY's Avatar
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    Im not 100% but im pretty sure the Nic doesnt wear hardly at all.Its much stronger than the rings as the rings wear before anything.Maybe after 250-300 hours the Nic might start to thin a little.

  10. #10
    Me Hahn and Joe H204YOU's Avatar
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    Quote Originally Posted by philip_gpr View Post
    OK, I am curious

    How thick is the nicasil?

    How can you tell if a used cylinder has enough plating left or if it is worn down too thin?

    I would think there is a limit on how much you can hone off?

    Is it possible to measure this this or tell by looking at a cylinder?
    I wanna say its about.035,cant remember but I know theres enough to hone any cyl to the C size.Most of the top wrenches do it when replacing more than one piston so things are uniform across the board,balanced,and even though its a very small increase most favor any increase in size available.

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