Moped Army

Iv got a 78 maxi 2hp with 12mmbing after about a mile of driving the engine makes a pinging sound and it will stall at idle. at first ithought timing was off so i set timing to full advance and largest gap at points. this made it run better and faster but didnt fix the overheating problem. the stock jet that wasin the carb was a 60 i upped it to a 62 .. help