You adjusted the valves, so one thing to cross off. Do you have the choke on the proper setting (don't ask how I know that one
)? Where it should be set to 'off' can sometimes be confusing on Chinabikes. Did you put in a new (quality) plug? The stock ones can be crappy. Ask Barnone on his thread for his advice if you haven't already done so since he has the same bike.
Edit: didn't read down far enough, so good thing you solved it!! Jerryhawk is good at diagnosing!!!
I would still suggest a new plug if you haven't already done so.