quits

I rode it sixteen miles today on it's maiden voyage. Put a KTM fuel sock in at the dealer's yesterday when I picked it up new. Put 1 1/2 gallons of 91 octane Arco in and rode it for sixteen miles of mixed dirt and asphalt to the top of Santa Rita Creek Road. On my way back down (coming home)...

I have a 2010 FE570 with about 30 hours. The bike, after it has been run for a while, starts to backfire and eventually quits. It will turn over but won't start until it has cooled down. When it does start it runs completely normal. The problem is getting worse as time goes on. What should...