Riding home from work tonight, and about 5 minutes into the ride, I heard this POP!, almost like a backfire. When I got home, I notice my oil tank cover was half off, and the temp gauge cap looked askew. On further investigation, the top to the tank is separated from the body right along the seam around the top edge. Apparently, what I heard was the tank exploding. What would cause this? Anyone else with this experience? Bike was running fine, before and after. No missing, it seemed to pull strong, as usual. I could touch the side of the rocker box covers when I got home, and they were warm, but not unusually so. It sounded like a random backfire. I was slowing down for a stop sign and turn. Based on where I heard the "backfire", and my normal commute time, I did ride it for about 7 minutes after it happened. The only thing that was a little "odd" was that it was a bit chilly, about 15, but I have ridden in those conditions many times--down to 10 or so. I did have to pump the throttle a bit to get it started and running for the first minute or so, but that is typical when it is this cold. The tank separated at the top seam, and popped the cover partially off. It did not lose any oil. I run AMSOIL 20-50. When I drained the oil out of the tank, I did notice some light color with it, like there was a bit of moisture in it at first, but it was pretty limited. If the breather hose that drains from the heads became frozen shut would that create backpressure through the oiling system? By the way, this top end has about 600 miles on it. I suppose a compression check is in order.