Bought a decent looking 314 for 400$ a couple weeks ago. Did not run, old owner said it needed a carb. Bought one of those cheap chinese knock off carbs off ebay (not ideal i know), new points/condenser, new plug, set points gap, fresh oil change, new battery. It runs now but its doing some strange things, will run fine for a little till its nice and warm then it will steadily start losing power, it will start blowing black smoke and now amount of carb tuning seems to pull it out of this once it starts doing it. Plugs are getting sooty black pretty quickly which i know is a rich condition but i just cant seem to get this thing tuned. Is there something else im missing, maybe a coil going bad?