can't find a diagram.. look at the attached pic. Not great but it might give you an idea.
my bike's head has the little hole but the hole empties in into the exhaust port..
springs can be found at a hardware store..
Don't be afraid to remove the head and look..
It's your bike and you're gonna have to get familiar with it someday..
Mopeds are self inflicted, entry-level mechanical experience.. take it or leave it.