Over-bore question Are pistons universal?
  • greenwr
    Posts: 5
    Are Pistons universal? I'm getting a new cylinder that's been over-bored to 74mm. Stock size was 68mm Can I use any 74mm piston with this new cylinder?

    Thanks!
  • NZriderNZrider
    Posts: 4,156
    no pistons arent universal. the height from the piston pin to the top of the dome is also critical and so is the skirt length and shape
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • masterlinkmasterlink
    Posts: 9,537
    NZriderno pistons arent universal. the height from the piston pit to the top of the dome is also critical and so is the skirt length and shape
    shape?? arent all pistons "piston shaped"?? :D
    image
    herby ur useless. MAPLE 2010
    Suzukidude, shut up. CS 2010

    So forward thinking everything else seems SDRAWKCAB.
  • toddincharlottetoddincharlotte
    Posts: 1,357
    masterlink
    NZriderno pistons arent universal. the height from the piston pit to the top of the dome is also critical and so is the skirt length and shape
    shape?? arent all pistons "piston shaped"?? :D
    Some have shorter skirts than others and they are all different under the skirts.....you can sometimes tell by feel [with a finger] but I personally like to eyeball them myself.
    +
    +
    2008 RMZ450 "Zook"
    2007 CR85 "Red"
  • masterlinkmasterlink
    Posts: 9,537
    toddincharlotte
    masterlink
    NZriderno pistons arent universal. the height from the piston pit to the top of the dome is also critical and so is the skirt length and shape
    shape?? arent all pistons "piston shaped"?? :D
    Some have shorter skirts than others and they are all different under the skirts.....you can sometimes tell by feel [with a finger] but I personally like to eyeball them myself.
    image
    image
    herby ur useless. MAPLE 2010
    Suzukidude, shut up. CS 2010

    So forward thinking everything else seems SDRAWKCAB.
  • NZriderNZrider
    Posts: 4,156
    skirt shape. some have intake ports in the piston skirt. some dont.
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • yo_marcyo_marc
    Posts: 571
    Some pistons are oval too ;) :D
  • toddincharlottetoddincharlotte
    Posts: 1,357
    masterlink
    toddincharlotte
    masterlink
    NZriderno pistons arent universal. the height from the piston pit to the top of the dome is also critical and so is the skirt length and shape
    shape?? arent all pistons "piston shaped"?? :D
    Some have shorter skirts than others and they are all different under the skirts.....you can sometimes tell by feel [with a finger] but I personally like to eyeball them myself.
    image
    Secretaries......I mean....pistons.
    +
    +
    2008 RMZ450 "Zook"
    2007 CR85 "Red"
  • NZriderNZrider
    Posts: 4,156
    apparently all pistons are fractionally oval to allow for the extra metal expansion around the piston pin castings.

    I think its awesome the lengths honda go to to be original in their performance models
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • whyZ-2-5-0
    Posts: 25
    pistons aren't universal. they have different port openings for different bikes (2 stroke) and different valve grooves for different bikes (4 stroke) and height is also different for all pistons.
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