250x/300ex pistons

[hardkoratvmxr]

are all oversize pistons the same. liek can i get an .08 250x piston and it still be a true 300cc?

or is that not how it works because of the ccs?

[bwamos]

No.
The 300ex is a stroked version of the 250x.

You need to 330 kit (80mm piston; 6mm or 0.240 over) to make the 250x close to a 300.

The 250x has a 57.3mm stroke (300ex has 65.5mm).

300ex: 65.5mm x (40^2 x 3.14) = 329cc

250x: 57.3mm x (40^2 x 3.14) = 288cc

A 350kit (82mm) will get you to 302cc