I have an 03 450 that i bought new. The bike doesn't have much time on it at all. This spring I thought I would try re jetting it to take care of a low throttle opening stumble. Well i put in the jetting recommendations that I got off of this website and the bike runs terrible. I don't think its the new jetting because i put in the old jets and it didn't change. I have pulled off the carb several times and cleaned it meticulously. I know its not a passage or a circuit clogged in the carb itself. Basically the bike wont run off choke. whenever i take the choke off it backfires constantly and wont idle. To me it seems like there's a vacuum leak somewhere. I checked the intake boot and it looks fine. I also checked the vacuum diaphragm on the side of the carb and it too looks fine. Does anyone have any suggestions before I take it to the dealer and pay $60/hr?