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Old 09-21-2011, 08:52 PM
Nashville Kat's Avatar
Nashville Kat Nashville Kat is offline
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Join Date: Apr 2009
Location: Jacksonville, Florida
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Default Re: Can someone tell me the diameter of a 66 piston head?

Here's some math- correct me if I'm wrong-
and I don't know the depth of the stroke or the formula for cubic cc's

but isn't the surface volume of a piston head pi x radius squared?

50 cc motor- 40mm diameter means 20mm radius
20 x 20 (squared)= 400
400 x pi or 3.14= 1256 square mm.

"66" motor 47 diameter means 23.5 radius
23.5 x 23.5= 552.25
552.25 x 3.14= 1613.4065 square mm

the second figure should be roughly 117.5% ?
This is the surface area of the piston heads

It's obviously not - it's almost another 1/3 again- or 33% more- so I guess I'm leaving the pi r squared formula off the percentage figure.

33% more then gives us an 18.888 figure- making the motor, with the same stroke- actually a 68.888 cc motor

but of course I've roughed up on the figure to 33- it's not quite and I'm through doing math for the night.
so anyway it's then a little bit LESS than 68.888 cc so maybe 66 is pretty acurate

I think

Last edited by Nashville Kat; 09-21-2011 at 09:02 PM.
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