I've had K&N air filters (and cabin filters, too, but that's a different story) for years on my pickups and speedster. Yes, the K&Ns must be oiled to work properly because the oil is what really traps the dust particles. The dirtier they get, the better they filter. Reading the K&N user manual, they recommend cleaning and re-oiling every 50,000 miles - maybe the lifetime of some of these Speedsters - but I clean and re-oil every four years because I'm OCD. Wash them with their cleaner stuff and a moderate-flow garden hose (or in a spare sink if your wife isn't home), tap to remove excess water and then let dry overnight. Next morning, spray the elements with the oil aerosol. Let sit 30 minutes then re-spray to catch any spots you missed originally.
I always run a 1/8"-3/16" bead of auto grease around the mating surfaces of the filter elements and the top and bottom plates of the air cleaner housing to seal everything up when put together. That prevents sucking crud in around the element once installed. If the elements don't fit nicely over your bottom plates, try squeezing them at the equator to make them slimmer and longer and they should pop right on.