Having managed to get the front brake working well thanks to advice here, my original concern that I might need to install a Brembo or other replacement master cylinder to get good brakes is no longer relevant.
My goal with this bike is to have it as original-looking as possible. For example, I recently purchased new shocks that match the originals, replacing the Hagons that were on the bike. The Hagons worked perfectly well but were not all-chrome as were the originals.
SO...I'm trying to determine what was the correct master cylinder cap for a 1976 UK CB400. I haven't been able to find a definitive period ad/brochure, etc to clarify that. Below are the two examples (from DS). Can anyone tell me which cap would have been on a new, UK 1976 model? I have seen a German ad from '76 and it has the "WARNING" cap but I can't find anything to definitely show if the UK model had that or the other cap.
I can't find a reference to "J1703" brake fluid earlier than 2001 which would indicate that that cap would not have been on a 1976 motorcycle but I want to verify that.