Read through this. Its a good tutorial. It's for a different bike, but for the nost part these are all the same.
http://chinariders.net/modules.php?n...ewtopic&t=1655
If the filters are foam, wash them in dish soap and water, or kerosine, mineral spirits, or diesel. Gasoline is a little too dangerous. I use diesel or mineral spirits, whichever is closer
. Let them dry thoroughly and reoil them with foam filter oil. I suppose you could use regular motor oil as well. If they are paper, the best you can do is blow them out with compressed air.