Originally Posted by SteveP

The CL3B and the CL7B are the same bore and stroke, so a head button from a CL7B is what you need. You can't use the head button from the Evo because it's a short-stroke engine with a slightly bigger bore. If you're installing a used head button, be sure to remove the glow plug - when the plug is installed, the button may not be able to fit in the bore.