Before taking my ATV to the dealer today, I decided to try to pinpoint the noise so I could be very specific when I described the problem to them. I took the machine over to my mom's yard, where she's got a lot more room than in my yard, and rode it around a bit, pushed and pulled it with the engine off, bounced up and down on it, and I never could get it to make the noise that it was making during the ride on Saturday. I thought that perhaps it needed to be ridden for a while to get it warmed up before it would make the noise again, so I went for a ride up on Wood Hill. I don't really know what I was thinking (other than that I probably wasn't thinking at all), but there were some dark clouds rolling in when I left my house, and I didn't even consider that I might get cold and wet on this ride. I was planning on sticking to the gas well roads north of town so that if something catastrophic did happen to the ATV, I'd easily be able to pick it up with the truck. Once I topped Wood Hill, I saw lightning hit the ground about a mile away. Shortly after that, the wind really picked up and it started raining. I was wearing only shorts and a t-shirt, and my entire left side was soaked while the right side was dry. I pulled off the road and found a pair of pinyon pines large enough to shelter me and the ATV, and I hunkered down for 20 minutes until the worst of the rain cleared up. There was another wave of dark clouds behind the first, so instead of continuing on the ride, I just headed back to the truck and called it a day. The ATV never did make the noise again, and once on the way back I found a long steep hill to roll down with the engine off, but the only sound was that of the tires on gravel. I only got about 10 miles in, but I think I'll do it again tomorrow and try to ride closer to 50 miles, possibly with some more weight on the rear, and definitely more prepared for the weather. If I can't get the noise to recur after that, I guess I'll have to write it off as a fluke, though I'll be pretty wary of riding in remote areas in the near future.