Take off your seat. Take off your airbox lid. Take out your airfilter. Oil new K&N (aerosol canned K&N oil, just spray evenly over all) and place it in. Then take out your carb and install a jet-kit, or do some personal fine tuning if you have the time (on carb) . I dont know if the rappys have a clamp on or slip and seal like the warriors do. But if its not a clamp on, search ebay for a kit, (filter, outerwear, and adaptor for a clamp instaed of slip, it gives a better seal and has that extras insurance we would all like.
Ive also heard of some people not re-jetting on some bikes because theyre jetted a hair fat from factory, so the k&n did the leaning out for them. Im not sue how much I would trust this, but It could save time to.