I have a 2009 Yz 450F with 10 hrs on it.  I picked it up as a left over in january.  It has the worst clutch I have ever experienced on a motocross bike.  It needs constant adjustment by the clicker on the perch.  As the bike heats up it gets looser and looser.  If I dont keep up with it and adjust it I stall the bike because there is just about no clutch pull after a while.  Has anyone had this problem?