This '97 KLR250 will start, has a steady missfire at all engine speeds. It is missing so badly that it can't be ridden. The carb has been apart and carefully cleaned and inspected twice. The CDI box has been replaced with a used unit off a KLX. We have a 2nd used CDI box that has been tested, but made no difference. We checked the valvetrain, compression release arms for free travel, camshaft and set the valves. Plug has been replaced too. The only thing that has not been done is check the stator. Does anyone have any idea what to check next?