I have recently purchased a 2005 YZ450 and installed a JD Jetting kit. The bike runs great! I live in Colorado and tuned the bike to run between 3000ft and 6000ft. I did not adjust the pilot screw. Being that I live in Colorado my ride alttitudes can vary greatly, and this time of year, most riding can be between 4000ft nad 8000ft. Is there a setting or adjustment that will work for this alttitiude range? Thanks for the help!