Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
Brian, Have you had a look in the Aladdin's cave section on this forum.Loads of info and manuals.
What carbs are fitted !https://cupdf.com/document/cb550-carb-rebuild-pd46a-rebuild.html
Only mention i can find is page 178 which is the K3 supplement and refers to PD carbs and its 3rd groove for 550 but 2nd for 500(K3 500 never came to UK officially).There is also a carb setting table on page 165 (550F-A) which i find confusing.
There is also a carb setting table on page 165 (550F-A) which i find confusing.
Now to the question Brian has posted. The standard position seems to have been 4th from top. Source is an America Honda booklet with carb settings for several Honda's. BTW, based on all the info I was able to find, I have compiled an overview myself. I have limited my search for the oldstyle carbs like you have.