I came across this atv for free and I have already done the basics,clean the carb, change all the fluids, replaced loose bushings, repaced the battery,changed the fuel oil and air filters and cleaned it up.My problem is when it is cold it starts right up no choke and runs great but as it warms up to operating temp it runs extremely rough and quits.After I let it cool off it does the same thing. When it runs bad I noticed an increase of smoke in the exhaust and I smell unburned fuel in the exhaust.Any help would be great