300ex head on 250x base

[nismo]

i was reading somethign someone wrote on ebay and they said that they put a 300ex head on the 250x base and have 300cc now is this true? or will the motor have still 250cc(not exact but around this range)?
thanks

[Hals250x]

A 300EX and 250X head are essentially the same. So you haven't really changed anything. You still have a 250. There are only two ways to increase displacement, either bigger bore or longer stroke. You haven't done either.