what engine to use

[Ripitupfilms]

I am just wondering everyones opinion on what fourstroke 250 dirtbike engine i should use in a tricked 250r frame i just totally destroyed my 250x stroker engine and we are thinking about just putting in a more up to date engine in the frame

[markk]

Y dont u go bigger??? There is a guy in town, that put a 440ex in his 250x frame!!!!!