Hi, yes, I had the same problem, only on an Xciting, but I believe they share most of their innards. Anyway, a multimeter, as Karl suggested is a good start, you will have to measure resistance and voltage across the three yellow wires coming from the engine as a start. Resistance should not be over 0.5 ohms I believe and the voltage should be around 70 Volts AC. Check the wiring, mine was in tatters straight at the point where the cables exit the engine, one was completely broken off, so the battery was charging just about a tiny bit, so it kept a healthy battery somewhat alive during use, but it would die eventually and needed to be recharged every so often. If the cable is broken off you are in bad luck, I had to part the engine and rewire the thing, it took me a good deal of two weeks and had to drain fluids, remove rear wheel, swing arm, muffler, water pump cover and generator cover, find an oil resistant way of soldering heat and oil tolerant cables to existing ones, cocking up royally on the way and loosing the oil through piece, which I still do not have, basically a major-major hassle. The other probability is a misbehaving reg-rec, which is a simple swap operation
