1976 KD125 need help
So, I picked up a 1976 KD125 early this week. When I looked at it the bike started first kick and ran fine. I was told the top and bottom end of the motor were redone only a few months ago and hadnt been riden much since. The bike will pretty much start first kick everytime, but it will only run for about 15-20 seconds before it died. If you grab the throttle it will die faster. If you kick start the bike with the thottle open a bit it will start, rev up like it should and then die in about the same amount of time. I figured the carb was flooding. I started playing with the idle speed screw and what I presume to be the mixture screw. That did nothing. I pulled the carb off and cleaned it out with carb cleaner, but the carb seemed pretty clean to begin with. So no i really don't know what to look at next. The bike will run for a little bit so I assume it is not a spark or compression issue. The spark plug is brand new too. I would really appreciate the help.
I spend $300 on this bike expecting to have to tinker with it, but the previous owner started if and drove it around his house with no issues.