howdy
Go on put a crf450 lump in, 250 are not worth it. At the moment a few of my freinds use 450 for super moto and they are the nuts, wheelies everywere off the throttle etc, and the roll on responce is just a hoot.
I looked at putting a big lump in one of my frames years ago and it seemed a lot of work, I have a rg500 with a moddied frame now, plus my nsr's if the four stroke moto x lumps were as good then as they are now i would not of hesitated to put one in, cause ive gone through enough bloody nsr engines to last a lifetime.
Oh yeah you can get 490 kits for the crf's mucho torque!! and just think of that under seat pipe as well, oh yes..
luke
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Farting is funny