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  1. #1
    Flying Scotsman's Avatar
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    Squish and bore clearance.

    I am rebuilding 2 old GP1200 engines.

    97 will have 150psi head with Wiseco pistons 84mm.
    99 will have 150psi head with 85.5 or 86mm pro,x pistons.(ported)FP.

    What should the squish be for both these engines.
    What should the bore clearance be for both these engines.
    SCOTT............
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  2. #2
    Pistonwash's Avatar
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    I am rebuilding 2 old GP1200 engines.

    97 will have 150psi head with Wiseco pistons 84mm.
    99 will have 150psi head with 85.5 or 86mm pro,x pistons.(ported)FP.

    What should the squish be for both these engines.
    What should the bore clearance be for both these engines.
    Squish should be between .060 -.070 for pump gas. The Wisecos need at least .0055 piston clearance, any less and you're gonna seize them. I hate Wisecos.

    On the Pro-x pistons..0045 clearance would be fine.

    You can actually go up to 165 lbs. of cranking compression and still run pump gas if you're gonna change domes. The 65u reacts well with a little extra oomph of compression.

  3. #3
    Flying Scotsman's Avatar
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    Thank's Mike,

    I have a question or two about measuring cylinders.Regarding specs in service manual.(When would be a good time to call you.)

    97 will have 165psi head with stock pistons .0045"-.005"bore clearance with .060"-.070"Squish.

    If I have to use the Wiseco pistons I will give another .001" clearance.

    99 Triple piper will have 150psi head 100+ octane ported cylinders 85.5-86mm Pro X pistons wih .0045"-.005" bore clearance what should squish be with race gas.

    I was thinking about marking the back of the domes with octane squish and psi for quik referance.
    Seems easy enough.

  4. #4
    Pistonwash's Avatar
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    I pm-ed you.

  5. #5
    ....back from the dead.... J-ME's Avatar
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    Just pulled the head off of Jumper again. NO deto with 175psi cranking comp. and 94 octane. That is with some occasional 10 minutes WOT.

    Woohoo. Piston wash looked great too. SOMEBODY knew what they were doing when the put this thing together.

  6. #6
    Flying Scotsman's Avatar
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    JUMPER still rocks.
    You go J-ME.........................

  7. #7
    ....back from the dead.... J-ME's Avatar
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    How's the indoor engine overhaul going?

    It's warming up here a bit, starting to get the riding itch again.

    BUT not until I check the carbs out for the season. Gotta send the POS Tiny Tach out for warranty repair too.

    Hah I came across this too. Who does this guy think he is?
    Read down some.
    http://rivaforums.com/groupee/forums...514#1926030514

  8. #8
    Pistonwash's Avatar
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