First off K&N does not make a air filter for our bike.
What is out there is a knock off.
K&N does not flow any more air then stock and if it does its such a small amount you would never feel any gain in the seat of your pants or on a dyno.
Yes you can wash the knock off and sit around for a day or two letting it dry.
The knock off is what $54 bucks and the stock one is $18 buck.
The stock one should last you a hole year and if you want pull it out blow it off with the air compressor and put it back in all in twenty minuets.
How to tell if you stock filter is bad hold it up to a bright light and see if it looks dirty. The less light you see means it is dirty.
Please add your state and model of bike you have. Click user CP @ top of page and then far left click edit signature. Thanks