hi i recently got myself an 09 kx250f can anybody tell me if they burn much oil or a reason that i seem to using alot ? also it seems to be leaving a film of wet oil at the end of the exhaust pipe , ive been told that it shouldnt do this & that it should only leave a dry black carbon like deposit ? new to four strokes as previously rode 2 strokes so could it be the way im riding it or something more serious ?