I use uni foam filters and maxima filter oil. Works on dirtbikes so it's fine for a motorized bike. K&N are cotton gauze and when oiled properly they filter dirt fine but can restrict air flow a bit. With the knock off filters you get whatever they send, paper or gauze. Paper is fine if you bow it out and don't get it wet.
The problem cars have with K&N is the filter oil coats the MAF. MAP and carburetor cars don't have an issue.