I have a 2005 yfz450 that will die after it runs for like 10 to 20 minutes into the ride. It acts like its running out of gas when it has a full tank of gas. The mechanic that I took it to has no clue what the problem is. We changed the plug, CDI box and went through the carburetor. Runs strong till the time it wants to backfire then die like it ran out of gas. We let it set or a minute or two and it fires right back up and runs strong again. This problem just started after having it serviced. Any ideas would be great. Thanks in advance