Ok Premixed, I'm joining you, I have a 01 cr250 that I bought to get the engine from. I just picked up a clean 2002 cr250 for the chasis.
I don't need to modify the engine though, I'm an off road rider and the stock 01 is perfect for that.
I rode the 01 and 02 back to back, and the 01 feels so much stronger down low.