Hi, My name is Jon and I have a Carb question for you if that's ok. Figured i'd go right to someone who is knowledgeable on the subject rather than starting another jetting thread. Im looking to go from a stock 04 carb to a FCR carb off a 07 crf250. Do I need different size jetting with the new carb or do i use the same size jets for the fcr carb? Its on a 04 with 12:1 je piston, full 2 brothers exhaust, k&n with outerwear's, rear of airbox lid is cut off. I believe my current jetting is 180, 50 and third clip on the needle. runs real good but does have a backfire when letting off the throttle. Ive read tons of postings on the fcr but none that really answer my question.