question for greyracer or someone with displacement knowledge

4 replies to this topic
  • belongaj

Posted April 10, 2009 - 03:33 PM


I want to make sure I am legal in a class. I bought a kx 100 with a 2mm stroker crank in it. My daughter can race up to a 105 in the girls class. I want to make sure the bike is legal. The bore is stock at 52.5 and the stock stroke is 45.8 so the stroke must be 47.8

Can someone tell me what the cc's are for the bike. I do not know how to figure the displacement. All help would be appreciated. Thanks

  • Brad_Aus

Posted April 10, 2009 - 03:58 PM


Looks like you are at 103.5cc.. There is lots of displacement calculators readily available online

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  • grayracer513

Posted April 10, 2009 - 05:33 PM


Multiply half the bore by itself (square the radius), multiply that by Pi (3.1416), then multiply the result of that by the stroke.


The number you will come up with is cubic millimeters. Divide it by 1000 (move the decimal 3 places to the left), and you have your answer in cubic centimeters.

  • belongaj

Posted April 12, 2009 - 05:26 AM


I went and used an online calulator and came up with 103.5cc also. That was awesome. Thank you to those who responded.

  • trailman006

Posted April 12, 2009 - 05:42 AM


Thats cool. I learned something new today. This place is great.

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