76.20mm is what size bore?

[LathersR]

I got this guy who has a 330r he said the piston is 3inches wide. That converts to 76.20mm so I'm trying to figure what bore it's on and what size it is at now. Also another measurement im trying to figure out is 68.26mm in a 310r.

[RichM1983]

76.2 mm bore with a stock stroke is 328cc.

The 68.26 with a stock stroke is 263cc

[LathersR]

So the 310 isn't a 310? It's a ct big bore cylinder. Is this cylinder a 265 big bore from ct?

[deathman53]

a 310 by most companies is 72mm bore x 72mm stroke and it equals to a 293, on the last bore of the cylinder 74mm, I think, is 309cc's. For a true 330 would be 76.5 bore x 72mm stroke. You have 328cc's.

[LathersR]

The 68.26 with a stock stroke is 263cc but is that a 265 big bore or a 310 big bore?

[LathersR]

obviously it is a 265 right?

[deathman53]

no, to many companies a 68mm bore is a 265, but its really 261cc's, 72mm bore is a 310 to most companies(really a 293cc). A 265 is not considered a big bore, as it fits i the stock sleeve, on the stock sleeve 69.5 is last bore, it comes to a 273, the sleeve is paper thin.

[LathersR]

So I bought a 250-265 cylinder instead of a 310.. what do you think it is worth? Anywhere close to a 310?

[deathman53]

it can be just as fast w/ the right pipe, porting, carb and reeds. I like pv's myself, they take away to the hard hit and make smoother power.