I have a tao tao 50cc that won’t run

For starters it’s been running without a exhaust for probably 3 months now. It’s been hard to start I just figured it was the valves. I just did a valve adjustment on it. I can get it to run (sometimes) for 30 seconds and then it shuts off and won’t run again no matter what. I re checked the valves, checked spark and cleaned the plug because the bikes been fouling the plug (coming out black and wet) it’s also been losing compression and smoking out the valve cover and exhaust. I checked my fuel system and cleaned my carb I’ve been working on it for days and can’t figure it out. Do you guys think it’s blown? The plug has been fouled before but I clean it and it appears to get spark when I check.