not quite sure, but depending on what kinda bike ur talking about it could be either or.
if ur talking mx bikes (250f or 250 2 stroke), the it would beat a 400 anyday.
but if ur talking 250 trail (4 stroke), then the 400 would be faster
400s are strictly trail bikes, and i have one, and modified they can go up to 80mph, so judge based on that