UNI filters come with a wire insert that supports the filter. The insert has a plastic collar, where it fits into the air intake boot. You need to inspect these collars each time you clean your filter! Over time, the plastic collar on the insert may compress from the pressure of the metal band that holds the filter in place, and will begin to take on a taper and will eventually no longer fit tightly into the intake. At this point, it needs to be replaced.

Another caution, at the time this was written the UNI catalog appears to have a lot of errors!

On my 400EX and 450R, my collars have compressed over a period of a little over a year or so. The collars ended up looking tapered (but like they were manufactured that way), rather than being square. It fooled me for a while, and if you like you can read the whole convoluted story here........ http://forums.atvconnection.com/mess...did/471223.cfm

 

My solution, at least for the 400EX and 450R.

http://forums.atvconnection.com/mess...TARTPAGE/1.cfm