The 250R is going to win
The 400ex its got a bigger motor... :P
One can see a video of a Honda CBR250RR in action from YouTube with the following titles; Kawasaki Ninja 250R vs. Honda CBR250R-Bonus Video, Honda CBR250R video-HondaCBR250 cc bike for India video review, and 2013 Honda CBR250R walk around video and on sale at Honda Chattanooga.
If they both are stock then they are about the same. I would rather have the yamie though their more reliable.
Translogic - 2010 Honda CR-Z vs S2000 vs Insight was released on: USA: 27 September 2010
If you are looking at the fastest production versions of either car (ex: RSX Type S vs. Prelude VTEC), then the RSX would about match with the Prelude 0-60, but be a little faster in the quarter mile.
Translogic - 2010 Honda CRZ vs- S2000 vs- Insight 1-24 was released on: USA: 27 September 2010
ZR1 is considerably faster
Clash of Warriors - 2002 Stilwell vs- Honda 1-3 was released on: USA: 2002
a z06 vs 302E= 302E
trx wins.
Motorweek - 1987 Honda Insight vs- Toyota Prius 28-43 was released on: USA: 26 June 2009