the studs need to be sealed where they screw into the case. the holes were drilled and tapped into the oil galley behind the cylinder. double nut the studs at top, tighten them togrther, and unscrew using the bottom nut. apply a sealant to the threads on the stud and reinstall them. then using the top nut, tighten to specs. also, the studs are exposed between the head and case, so that may not be carbon, but actually dirt. the copper washers are availeable from honda and should be replaced if they are flattened out. still availeable from honda. they should not gall the head as they are a soft material. clean the area with scrotchbrite and check the surface. I have not had any problem with any of my cbxs. note there are two different sizes of washers. hope this book I wrote helps!
