The '00 XR650 I just bought had a k&N air filter, and the previous owner boasted this as the only improvement he made to the bike. Personally, I would rather have the oem foam unit; which he did not know where it was at. Upon removal of the side panel I noticed the sealing edge of the airbox had gottenhot at one point or another and disfigured the joint. There was no spark aresting screen in the airbox. I guess the bike back fired and ignited the foam filter smothered in flamable filter oil. Any seconds to my notion?