I have a 1998 300ex that starts fine and rides fine but after about running for about ten minutes it dies and wont start for a couple minutes. I wanna say it might be to tight of exhaust valve but was told it was a reg/rec problem. any ideas.

 

The first thing I always check on a machine with your symptoms is the fuel tank vent. This describes exactly how a machine acts when the vent is clogged. First, you can always pull the vent tube and check it/blow compressed air through, etc. The other quick test is this...
Next time ti acts up, shut the machine off(you need some quiet.) Slowly crack the gas cap. If you hear air rushing in, and the machine will start immediately after, you have diagnosed the problem. I actually ran my machine with the cap cracked during one mudfest of an xc race a few years ago, as my vent got clogged early on and couldn't afford the time to fix it.

 

Scooter has a great idea there, vacuum in the tank will prevent fuel from flowing to the carb. You may also be onto something, if it runs fine cold, then stalls when warm, it may be time for a valve clearance check. Electrical problems are also known to get worse with rising temp, you could have a bad coil/stator, or rectifier. Check the easier stuff first, like the tank vent and the valves, digging into the electrical can be time consuming and frustrating, so leave that for last.

 

I ran it with the gas cap cracked and it didn't change anything. After it died, I tried starting it again and it tried to start once or twice but that was it. I cranked it again and the battery started to die. Which is leading me to believe its either the reg/rec or stator I check the connection and all seemed good. i checked the battery with the key off and I'm at 11.56vdc (bad I know) cranking the battery drops to about 6-7 vdcwhat should i do next thanks for the help

 

yeah i knew a guy had a big bug in his tank, when he had the cap loose/off it ran, but when on it didnt , the bug would just whoooosh