YZF dies out

[Birdman]

2001 YZ250F. Riden in woods and raced at harescrambles. Original owner and bike has run perfectly since new (until now). Bike starts to backfire and eventually dies after about one hour and won't restart. After ten minutes or so, the bike runs fine for another hour.
Started running a shorty tank vent tube months before this problem started but haven't pulled it at time of problem to check if this is the culprit.
Ran 110 octane gas at a race this summer and that's when the bike started acting funny.
Had the dealer adjust the valves and made no difference.
Any advice before I start digging into stator / electrics?

 

[Yamaha0506]

Did you try switching back to the gas you used before the 110? Also ask your dealer if they have had any problems like that before. Good luck

 

[biglou]

Here's a quick check of something I just read about on ThumperTalk: Pull your hotstart button assembly out and make sure there is nothing cought up in the mechanism. No hunks of dirt, debris, etc. This is a quick thing to check, and your symptoms sound similar to the guy who posted on TT.