.10 over pistons

Discussion in 'Softail Models' started by astrorock, Jun 7, 2011.

  1. astrorock

    astrorock Member

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    Hay guys, been a while.. Thinking about going with .10 over pistons in my evo, what would the cubic inches change too? would i have to re-jett the carb again?
     
  2. BUBBIE

    BUBBIE Well-Known Member

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    Just a late night thought..

    when i went from 883cc to a 1200cc that was from a 3" piston to a 3 and 1/2" piston... Now that is big... 883 to 1200cc=74ci
    Compare the increase to the cc's

    IF you are saying .010 thousands increase in piston size, probably not enough to really add a Cubic inch...

    More than likely your tuning would stay the same on your carb. if it runs UN lean now, it should do fine..

    sounds like you are just cleaning up the bore? with new pistons and rings.

    BUT even if .10 of an inch would add some and not Much bigger but i think you meant .010 = ten thousands?

    give me a shout back if a .10 and some one will know the math.

    signed....BUBBIE
     
  3. karlsbike

    karlsbike Active Member

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    Stock piston diameter 3.498 => 81.69 in3
    .01 overbore piston 3.508 => 82.15 in3
    (not exactly the same as swept cylinder volume, as the cylinders are slightly more, but this is splitting hairs...)

    .46 in3 additional volume equals nothing in practise, but if your cylinders are worn a fresh hone with oversize pistons and rings (check if required for .01 over) will give you better sealing rings = less blow-by loss...
    No re-jetting needed.
     
  4. 98fat

    98fat Active Member

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    Why are you doing this? Need a little more info. If you want more punch do cams and port the heads.