alright heres my two sense.... had had many the same problems u 05-07 cr250r guys r having to rich down low and dead spot in power band before the mid range punch kicks in... here is the answer....... SEND IT TO ERIC GORR FOR MO BETTA PORTING!!!! i played with honda optional needles and jdkit(sucked waste of 70 bucks) here is my set up..
air screw (2 1/2 turns out)
pilot (37.5)
needle (stock 3rd clip)
main (410)
plug (br8eg)
v-force 3
these r my specs after ERIC GORR'S PORTING <---------single best mod for this bike. read my post in MODS AND PERFORMANCE forum for my ride report.