A friend and i are having major air filter issues, i with a 00' XR600 and him with a XR650. we have tried almost everything the searches came up with to remedy these issues. If you have had problems or have fixes please reply... Issue 1. 00'Xr600 bought with a twin air with a steel backfire screen inside it. Not sure what a stock filter looks like or if this is the screen from it or a actual twin air screen. also have uni and experiencing same problem.Problem is in dusty conditions obviously. Dust is getting around the filter and into the motor. actual grains of sand and dirt, not just light dust. Seems the internal cages that the 2 filters have don't posativley engage the steel lip inside the airbox, letting the filter move and possibly lift, letting the dirt in. There is a strip of foam running across the sealing surface of the filter and it seems the foam is suppost to squish around the lip and cage sealing itself. Does the stock filter do this? Is there a strip on the stock filter? is anyone cutting these strips from the filter or modding the sealing surface allowing the steel lip on the airbox itself to slip inside and thus sealing the filter and allowing a good fit? I have tried diff oils and grease on the sealing surface to no avail. I'm looking at cutting the filters to fit better. Can someone tell me what a stock filter looks like for the 600? Issue 2. 01 XR650R. Uni filter with grease on the lip. Just removed the air filter after a dusty day of riding and the inside of the airbox is completly coated with dirt and dust. Is the K&N the way to fly with this bike? The motor is smoking pretty badly now. Looked as if dirt was getting pulled through the filter as well as around it, but i'm guessing the back was dirty from the general dust floating around the airbox. How are you guys sealing your airbox on this bike? What about that foam seal from PC racing? Wht filters actually work? Any helpful reply is greatly appreciated.