I have a 08 yz405f. Stock jetting. Valves in spec. I have about 25 hours on it. The bike just randomly stalls about once every 30 min or so of trail riding. I am not stalling the bike... today I was going over a double log crossing and right in the middle it just sputtered out. I didn't hear a pop or a cough. I ride trail in florida. Any ideas would be appreciated.