In my experience, these china girls need a lot of tuning. My advise (and it's probably contrary to some of the guys here) would be to get rid of that carb and get an R/T speed carb. Besides re-jetting, they basically don't need tuned. Check your intake and exhaust gaskets, these are common compression leak areas (sounds like a compression leak to me) but also check your base gasket too. If you can keep it running while idle, try looking around to see if you can see where fuel might be bubbling out while it's running, higher RPMs usually make it more noticeable. There are a number of places or things it could be. The more you work on these, the more you learn about them.