Yamoto 150cc
 

Hi folks, just joined a few minutes ago because forums have been my best resources for mechanical issues when your a backyard mechanic. This past summer I purchased a yamoto 150cc quad for my grandson who will be 9 next month and all was well other than it would not keep the battery charged which I knew when I bought it. The seller said it needed a new battery which I replaced but found that there was a charging issue soon after we bought it. I tool it to a neighbor who works on motorcycles and quads himself, he put in a new stater and another electronic box of some sort. My grandson has ridden it 2 or 3 times since with no real issues other than once in a while it starts idling a little rough then, it quits but starts right back up. The thing never came with a air filter which I ordered but wont fit up in front above the headlights where I think its supposed to go. The big issue today is I tried to start it up and would barely run (cold blooded) then stop, start it again and the same thing till I wore the battery down. I then hooked the charger to the terminals and now the thing wont fire up at all. Now my question is,am I blowing something out electronically when I hook the charger to the terminals on the battery?