Hello Mr Euphonius!
I've been to jiaoji lu billions of times and i cant believe I've never saw the minibike store that you talked about in your post!! Is it further down the street from the shop with all the tricked out yamaha jogs and cygnuses? Those minibikes look like so much fun to just fool around on. Mr muffler man is just the kind of guy i need, I'm restoring my Jincheong 50 (basically exactly the same as a honda chaly) and ive been trying to fit a new pipe on, but the problem is that it's so old that no where has any spare parts, but I bet this muffler master can help me out somehow.
Thanks for the post!