When you say you have a manual that addresses earlier years, doesn't that manual include supplemental information in the back? I mean, does the manual cover the 99 model? If it's a Clymer, then there is info in the back. Otherwise, http://s7d2.scene7.com/is/image/Motosport/KX250%5E1999%5ECYLINDER%20HEAD-CYLINDER?$oemlarge$
From the looks of it, there appears to be a pin or something that is holding the valve in place. Maybe you can get at it from the side triangular hole in the cyl.
|