I have a coolster 125cc xr8b. I had used for about 4 months over winter ran fine when I out it away. Battery was dead. Out new battery in and smoke started coming out of case on left side of the engine where the alternator is. Alternator winding was heating up extremely hot and burned up, the lower winding piece of the assembly. I figured it had a short and put a new one in but the same thing happened. I am trying to figure out what is causing this. Any ideas.

 

Firstly check the terminals on the battery, identically sized batteries can have the positive and negative terminals the opposite way round. Then change the regulator, it would probably be the cause of your problems, but even if it wasn’t, it will be fried now. Check the wiring to the regulator, normally yellow wires from alternator to regulator, red to battery positive and black or green to negative.