the thread size of 1 1/16 x 20tpi is UNF form, close enough for my purposes -- making a tool to pull the fork tubes into the top yoke, and also to break the taper when removing the tubes. I believe that the difference between UNF and CEI threads is probably the thread form, radius or truncation of the root and / or crest of the thread. When I screwed a 1 1/16 x 20 UNF tap into an old fork tube ( BSA ) a small amount of material was shaved. Thanks for the attention to my question.
James.