While riding an enduro last weekend, I ran out of gas. As I ran out, bike went to screaming just before it died. I switched to reserve and after starting back up, I had a tick noise. After monkeying around some, it seems to be coming from the right front of the engine. It sounded as if it was originating at the water pump, so I popped the cover off, and all seems well. The tick seems to increase and decrease in frequency following engine revs. What to check next, the PV? Any other ideas?