Bore size to cc

• Bore size to cc
  Posted by Ywnmn on 26 Oct, 2014 14:05
• I have a weisco piston (86.5) in my zilla. I hear everyone say there's is 20 over or 50 over or 100 over ect... What would mine be and why? I guess it's important to know these things about your machine, IDK. Appreciate any input. Thanks
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• #1 Reply
  Posted by OldMan on 26 Oct, 2014 16:03
• Its .50mm over stock making the displacement 505 cc
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• #2 Reply
  Posted by ZillaFreak on 27 Oct, 2014 04:03
• When people say 20 over, them mean the pistons is .020" bigger than stock. .508mm = .020 inch.
  
  These are overbores.
  .25mm = .010"
  .50mm = .020"
  .75mm = .030"
  1mm = .040"
  ect
  
  If stock piston size is 64mm, and you have 64.5mm, you have a .020" overbore piston in there.
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