I am not sure about this all my 1100's are 12mm with 1.25 pitch take a spark plug and measure it..and it's easy to make form form an old plug..knock out the center..tap the top to fit the adapter you have and you are good to go.
I am sorry and stand corrected they are the 12 mm threads.. I found this out a couple of days ago.. I sincerely apologize for the mistake.. and that is why we look out for each other on here!!