Lash,

Like stated 1 over in this case is 1mm.

Stock bore diameter = 61mm, radius = 1/2 bore diameter or 30.5mm

1mm over diameter = 62mm, radius = 1/2 bore diameter or 31mm

StockStroke = 63mm

Using the old formula for "volume of a cylinder". Several variations exist now.

Volume of a cylinder formula is stated as V=πr2h

V (Volume) =(equals) π (pi 3.1415) r2 (radius x radius) h (height/ stroke)

Entering your values in the equation

V= 3.1415, times, (31)2 or 961, times, 63 (stock stroke)

V= 3.1415 x 961 x 63

V= 190,195.834 cubic Millimeters or 190.195834 cubic centimeters

Volume for 1 cylinder with a 62mm bore and 63mm stroke equals 190.195834cc

Total displacement for all 4 cylinders = 4 x 190.195834

Total displaced Volume = 760.783338 cc

That's the Math their talking about. This example doesn't include piston to cylinder wall clearance. Their are other equations that help eliminate "order of operations" mistakes. Better yet there are online displacement calculators that don't make any mistakes.

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