ive got a 2002 400ex if i maintain either 1/4 throttle or full its fine but in between its spits and sputters and cuts out REALLY bad...got a new spark plug and just cleaned the carb...dont know where else to look...suggestions please?
what are all the settings of your carb and any mods done to the bike?... sounds like it is really lean... like it is jetted for the complete airbox and you left the lid off?
more details are needed to give you a better answer.