please could you give me some help with this. i have 00 wr400 yz timed,yoshi,white header,white power filter.mobil 1 oil,ekn#3,100paj,45pj,170mj. pj 2 turns,I put in the ekn and 100pj last weekend it never had a bog or ran rich before,now if i snap the throttle it gives a little burp and then takes off like a stabbed rat!great wheelies too. should i drop the needle to #2 or do the b.k. mod, or mixture screw adjustment. i ride at about 3000- 4000ft at 20-30c near sydney.thank you everyone for all the other topics.