My 2001 warrior 350 has been sputtering and popping at high rpms. I changed the plugs. I am pretty sure it is jetting but the person i got it off of didn't know anything as he was selling it for a friend. Anyone know what the problem could be? just cleaned the carb a few weeks ago. it also has a aftermarket filter

 

do a plug chop that will tell you if it is jetting. Ive also had them do that and it was a weak stator. Also a bad carb boot could cause it.