After having my 98 WR 400 since late 99, and NEVER having any problems with it, it finally died today...in a BIG way. I was riding about 40 mph and noticed a slight churring sound (or something close to it), then a SNAP and then nothing. The motor went dead and the tire locked up. I shifted to neutral, the bike rolls, but the motor is seized. After beginning to tear down the bike to see what I could see, I found (just below the carb and behind the cylinder, where the cavity is that looks like it was made for a starter) two pieces of the case just sitting there, right next to the hole they used to cover. So, I'm not sure what it was that busted yet, but it's definitely in the lower end, behind the cylinder. I'm guessing maybe the primary drive? I have't seen the inside of one of these yet, so I'm just guessing. Anyone have any inputs? Also, what kind of cost is associated with a complete engine rebuild (cases included)? Thanks, and have fun next weekend in Ocala Forest...that's where I was riding!