Here's a good one for you all to take in....check the slide in your carb often. There is a little metal piece on the engine side of the throttle valve on the 99 YZ400. It likes to crack and get sucked into the engine. This happend to me when I was 25 miles from my truck. I was fortunate enough to have mine come in half and wedge itself in the intake, therefore allowing for a 4000 rpm idle and a fun ride back. At least it didn't make it into the engine. Apparently I am not alone so please check yours...also frequently change your oil filter. I have only recently begun this ritual and you can't believe what you see in it..... PS anybody ride in colorado?