[aaa]

So i bought a boom vader around 2 months back and havent had the best experience. Out the box i changed the oil, carb, and sprocket. I didnt clean the gas tank or replace the fuel line (I will probable replace fuel line soon).
Problem is, the bike starts when it feels like it and on a good day itll drive for like 30 minutes, then starts jerking, dieing and not starting anymore. then a few minutes later it might start again for like 5 minutes. I already replaced the battery and spark plug. the spark plug got dark as hell for 50 miles. Im new to bikes and carbs so if someone could please help id appreciate it a lot.