I have a 2007 yz450, put in the JD jet kit, and Zip Ty fuel screw. Just bought a 2009 yz450f, and put the carb from my '07 into the '09. First ride on the 09 and the bike will stutter at lower rpms, and runs good with the throttle all open. 2 questions: 1: There shouldn't be a problem putting the 07 carb into the 09, right? 2: Could it just be fuel screw settings? I shouldn't have to re-jet it right? Thanks in advance!