his kfx450 is stock my 250r has a 350 powervalve cylinder with stage 3 porting and a lectron carb with rad valves and a full paul turner exaust he thinks he will win what do you think

 

deffinatly not.
because, (eventhough its different) the dirt bike racing they have to use 250 2strokes to race 450 4strokes.
also there is a video that i saw with a blaster and a 310 kit racing a 450 and it killed it by like 4-5 quad lengths.
the 250r's stock give a 400 a run for its money with a 350 kit in a 250r it shouldnt even be a race.

 

Not if he is stock. The KFX comes fairly corked up. Modified...who knows...

 

250R all the way.

 

250!!!!!!!!!!!!!!!!!!!!!!!!!!

 

2 fiddy r , excuse me 3 fiddy r

 

Your 250 should kill it. I'll race any of the 450's with mine, but mines no where near stock either.