Hi guys im new here and i already have a problem with my 400. When i pull start it, it makes a weird sound. And then when i start to push the throttle, it just shuts off. The sound is like when an atv shuts off it sometimes makes a loud "pop" sound. The sound on mine is like that "pop" over and over again, with each turnover of the engine. One time it even made a spark down on part where i put my left foot when i tried to push the throttle. Any ideas?? Please help!