Motorcycle Repair: Kawasaki EX 250 not running when engines warm., header pipes, premium gasoline

Question
I have a 1995 Kawasaki Ex 250. It was running fine until last week when I was riding it. For some reason that I don't know when the engine's temperature needle reach midpoint, the engine would sputter and die unless I keep the throttle open. After about 5-8 minutes of running with the throttle open, it would eventually die on it's own even if the throttle is wide open and the bike would not start anymore. It would need to cool down or wait till the next day/morning and it would start fine. Then it will go to the same cycle again. I also noticed that my header pipes glows bright pink/red when the engine's hot. I pulled the carbs 4 times and thoroughly cleaned it including all the jets. Carbs are synch as well. I adjusted the valve to specs as well. Intake is .004 and .006 for the exhaust. Gas in tank is new and fresh. I'm even using 92 octane premium gasoline. Air filter is clean and spark plugs are new NGK's. I'm really lost and don't know what to do next. Please help me Collins. Thank you in advance.

Answer
If your pipes r heating up that much then u r EXTREMELY lean on air/fuel mix.  Let me consider this somemore and get back 2 u!

I have a 1995 Kawasaki Ex 250. It was running fine until last week when I was riding it. For some reason that I don't know when the engine's temperature needle reach midpoint, the engine would sputter and die unless I keep the throttle open. After about 5-8 minutes of running with the throttle open, it would eventually die on it's own even if the throttle is wide open and the bike would not start anymore. It would need to cool down or wait till the next day/morning and it would start fine. Then it will go to the same cycle again. I also noticed that my header pipes glows bright pink/red when the engine's hot. I pulled the carbs 4 times and thoroughly cleaned it including all the jets. Carbs are synch as well. I adjusted the valve to specs as well. Intake is .004 and .006 for the exhaust. Gas in tank is new and fresh. I'm even using 92 octane premium gasoline. Air filter is clean and spark plugs are new NGK's. I'm really lost and don't know what to do next. Please help me Collins. Thank you in advance.