Yea i put a new plug in it when it happened. i tore the whole top end down thinkn i stuck a piston & found nothing wrong. i put it all back together & took it out riding in the dunes last week & still the same thing sputtering on top end only. It had new fuel in it too. Im completely stumped. The plug even looks good when i check it granted its a new plug but nothing out of the ordinary with the plug. I empty the tank after every ride & drain the carb. On low & mid range its a totally normal ride with the front wheels up & tryn not to get ripped off from the power... Jerry built me an ass kickn motor package & in 4yrs this is the only problem ive ever had with it. I called & e-mailed Jerry & havnt heard back from him & i know hes super swamped so i wanted to ask here to see if anyone would have a answer & thank you for your ideas.