CR250 cylinder spacer/base gaskets??

Discussion in 'Eric Gorr's Moto Tech Articles' started by CharlieT, Jul 1, 2005.

  1. CharlieT

    CharlieT Member
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    Finaly got to check the squish tonight on that top end I just bought. Like I told you when I called and checked, it cc'd out at around 11.5. Well the squish is at 10 thou.....and yes, if you try and spin it, it does hit!! (duh!)

    Do you have or know of anywhere to get rather thick base gaskets or a spacer? The base gaskets I have are around 11-12 thou. Does look like these old cases were decked at some time in the past.

    To raise it up to around 20-21cc's, about what thickness would I need?
     

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  2. bclapham

    bclapham Lifetime Sponsor

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    cometic sells gaskets in different thickness, or you can stack two.

    you can calculate the extra volume by simple math- the vol of a cylinder, pi x R squared x h. the gaskets are normally 0.5mm thick, whatever that means in "thous"
     
  3. CharlieT

    CharlieT Member
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    I checked that before and it came out that rounded off, a 0.010in increase should increase vol 1cc
    The gaskets I have are cometic and are measuring .011-12in, or around .28mm
    A .5mm gasket is roughly .020in thickness, I asume that must be the thicknes on a stock Honda base gasket??
    If the change in vol calc is correct, then it looks like I would need .080 to get it up around 20cc.
    If it is .010in on squish now, adding .080in to the base would increase the squish to .090. SO if I'm looking to get a squish around .40in, then I'm looking at taking .050 off the head.

    Of course, this is all predicated on a .010 increase truly equaling a 1cc increase.
     

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