Does anyone know of a kit, or conversion for the 250r to put a 400ex, 300ex, 250x, 350x, or possibly a yz426?

 

why would you wanna do something stupid like that????

the only two engines that i would consider for the swap would be the YZ or the 350...

and, contact laeger for info on putting the YZ engine in there...

 

yould be better off buying a new 400ex.. suspension geometry is almost identical if not better.. the frame is stronger not only because of the use of round tubing but as well if you have an original 250r the metal is old and has already suffered at least 13 years of abuse, this of course is all with cost effectiveness in mind. the yz426 conversion is the only mod id really look into but if i was going oin that direction id also look into purchasing a leagers or houser frame that a er designed to accomadate a 426