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I just bought a la sleeve 310 kit 72-72 bore stroke if im calculating this right that equates to 293cc why is it being sold as a "310". Anyways I've been told the pro x barrel has to be ported to gain full potential is this true? Would the standard porting i have be equilevent to say stock porting on a factory cylinder? Branden
 

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the 310 is the last bore on the cylinder. the port you could say is equiliant to say stock but a little better from the port layout .
 

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I think that if you calculate a 74 mm bore (max for a 310), you will come out to about 309 cc.
 

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Its just like any other cylinder stock or aftermarket, the CCs are always lower than the size the engine is listed as.
A stock R cylinder is 246cc but called a 250.

Check this out, the other day had two of the small chinese 4 stroke engines, one was listed as a 110cc the other was a 125cc. One cylinder had 107cc on the side & the other one had 123cc.This is cast into the cylinder.
Pulled each engine down, both had the same size piston & both had the same stroke crank & guess what, thats not the half of it, both of those engines measured out to be 90cc.

Boy I'm telling you :blink: , if it aint somthing.
All you got to remember is, Dec 7th 1941 a day that will go down in imfome, them ol boys kick our tails back then & looks like they are still kicking.
Neil
 

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lol neil. that really doesnt surprise me in the least.
 

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your post above Neil is why I also asked you to confirm the cc's for kiddo's motor ;)
 

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my piston says 72.95mm does anyone know if this is on its last or 2nd last bore?
also what to do on the last bore.. plate it or resleeve?
 

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my piston says 72.95mm does anyone know if this is on its last or 2nd last bore?
also what to do on the last bore.. plate it or resleeve?
It is the 2nd to last bore. The last piston is 73.50 mm for the 310.
 
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