Motorcycle Repair: Sportster runs bad after warmed up., sportster 1200, fuel cap

Question
QUESTION: I have a 2005 sportster 1200 with 2700 miles. The bike starts, warms up and runs great for about 12-15 miles. Then it is almost impossible to keep it running long enough to get you home. After it cools down it will run good again for another few miles.

ANSWER: Start the bike and let it warm up so it doesnt want to run. Pull the plugs. Are you getting a good spark?
Mike

---------- FOLLOW-UP ----------

QUESTION: I let the bike idle until it started running rough and finally died.(about 25 minutes) Then I pulled the plugs, both plugs appear to be getting good spark.

Answer
Ok, then take the bike for a ride and when it stops, look downt he throat of the carb and twist the throttle, are you getting a shot of fuel? If you arent, then run the bike without the fuel cap. Does it shut off? if it does, then the vent in the cap is plugged. If its not, then I would have to ignition modual tested. It might be breaking down when the bike gets hot
Good luck and happy riding
Mike