The front end of the 1990 VN750 I just bought seems exceedingly soft. My technical manual says that if I unscrew the caps at the top of the fork legs, a schraeder valve will allow me to add some pressure to the chamber of each leg. I unscrewed the caps at the top of the legs, but... no valve! There's something that looks like a valve (it's threaded), but there's no hole, no pin; in short, it's not a valve. Anybody know if I can get more stiffness in there without changing the springs? Thanks!