Every engine needs Fuel, Oxygen, and spark to run. FULLY check all 3, and replace anything that MIGHT be an issue ( bring a friend that knows a thing or two about cars/bikes )
Your bike have a fuel filter? Check it.
Take the carb off again and look it over, clean the shit out of it. Did you actually clean it or just look at/down it and say thats OK ?
Replace the plug regardless, if you havent since you bought it, or you cant remember the last time it was replaced.
if you do all of this, and the problem is still there, you might have an issue worth getting it checked out, maybe thats why the previous owner sold the bike?
/Because clearly this is a safety issue, so you can check all the small stuff first, or you can pay a guy at a shop $200 to do it to find out a fuel filter was plugged, or carb jets are plugged.
This post was edited by IB0T on Sep 5 2013 06:45am