I have a '03 YZ450. I think it may be running lean. What are the symptoms of a lean YZ450? It pops A LOT during deceleration but I also have a Yoshimura exhaust that has a slip on part. How can I tell if it's leaking? The bike also has Yoshimura head work but I don't know to what extent if that matters? I've never swapped out jets or anything before, how hard is it? Does anyone have a good guide w/ pics for switching jets? I live in Southern California and ride in 60-85 degree weather, what jet size would be correct? Just trying to figure this bike out... Thanks, Steve.