Hey guys. I just recently got a stock 02 yz426f and have a few questions on it. First off, the thing is a tank, and runs like a champ. However, in first and second gear, when you open it up, it chokes and sputters and almost dies. The bike is warmed up and has been running awhile at this point. (problem also happens when it's cold.) also, when you let off the throttle go in all gears, it's got a gnarly backfire. I've tried adjusting the air screw and haven't found that "sweet spot". Is there anything I can do specifically to help both issues? They seem related to the carb. Any input would help.