Its me once again. I have been unable to continue my frustrating attempt at getting my Yamaha Champ (very similar to QT50) since I have been waiting for a head (thats "A" not "some"!), and one has been found so I am ready to get back at it. I stripped the threads popping plugs in and out over and over. But there has been a new discovery adding to some more head scratching and thinking on my part. I spoke to the previous owner of the moped (there was only 1 ever) last week, and towards the end of his ownership described having the same problems that I was having originally which is starting, idling, and running fine for a few hours or miles whichever the case, and then coughing out and not restarting and finding a fouled plug. And judging by the blackness discovered with the original plug that I removed, as well as in cylinder and around bowl of head where combustion occurs, I take that it was indeed running too rich which is also where I am deriving this hypothesis. He also tells me that he invested approx $400 into it at a local Yamaha shop to get it into its running condition which included among a few other things not related, a ring job, new carb and cables, which would explain the extreme cleanliness of the carb upon disassembly.
As I noted before this "bike" is very similar to the QT50, but its main difference with exception to the tire size, is that my Champ (thats its name a.k.a LC50G) has an "auto" choke on it which operates off of vacuum and a device called a BVS valve which opens and closes based on the temperature which it gets from sitting on top of the head which is then sent to a check valve. Is it possible that any of these devices along the "auto" choke (dumb ass thing) are faulty? And if so how can I tell and/or how can I bypass it or rig up a manual one of my own? The QT50 has a manual thumb control, but that I asume would involve a carb from a QT50 as well. I have replaced all hoses involved with this operation so that factor has been eliminated. Anyone?