top end question

[hotrodbelair]

a buddy of mine has a 250r and wants to know if a 92 cr 250 top end will fit on a 86 250r bottom end. or would the piston or head fit?

[racerx573]

I have an older CR head that I used on my old 265, it's a lot higher compression than a stock R. FTZ makes kits to use a CR cylinder on a TRX bottom end, I don't believe the powervalve functions though, so it is blocked off. Also the the CR has better port mapping.