Hi I have a 2000 440ex I put a big bore on recently an it ran fine for a bout month and all of a sudden it started spit in and sputtering so I cleaned the carb and changed the spark plug adjusted the valves took lid off air box bigger jets and it will run if I hold the throttle and it will smoke white ive tried ajusting the air/fuel mixture will still not run right I dont know what else could be wrong please help if you know anything one more thing what is the compression sopose to be on a 440ex??