Do a search for Mosfet regulator rectifier or follow the link
. I have one if these and their awesome. Also I read somewhere that the zip ties on a stator can cause them to smoke out early - thus guy reckoned he removed them (carefully!!) and had no issues. Anyway, do some reading and have a go. I had similar charging issues, replaced the reg rec and did the stator thing, new wires and no issues since.