I guess i am a little confused. Why did you tear it apart and what did you tear apart? Did this problem just start all of the sudden or after you had done something to the quad? It is pretty hard to get the fuel line on wrong. If you tore the carbs apart for some reason you may have got your float messed up and it may not be getting enough fuel in the oone carb. One other question you plugs may look fine but how old are they? You may have a plug going bad.