how hard is it to bolt the yzf 400, 426, 450 engine in a 250r frame? got any pics? any full on instructions?

 

why? the YFZ already has a excellent chassis.

 

The 250r chassis is still better for MX and is still alighter machine, as for the actual question, I have no idea

 

As much as Id like to say the 250r is king I have to say (due only to the 20 some shootouts and articles Ive read) that the yamaha is superior to the "R". Yes it is hard to beleive that there could be something better (especially from yamaha) but face facts......its time had to come.
I guess if you meen "better" becuase of aftermarket support and so on sure I guess so but give it a year (probly less) and therll be about the same out. Otherwise technology is here FOR us!

 

Its not that hard its been done many times before. Thats what everyone did before the crf came out. Sorry no instructions