650SS twin 928 concentric carbs

Are you planning on buying Premiers, if so then go for the 19 pilots instead of the 17 pilots. Standard 4 stroke 928's would be fitted with a 25 pilot bush which will work fine as long as they are cleaned by boring out with a 16 thou drill.

You could always ask for Burlen’s recommended settings. When changing from twin monos to single concentric on my recent Dommie restoration, they supplied a carb to their recommended settings which worked perfectly from the very first start (first kick too!).

If they are NOS then they could be 2 stroke and not have the pilot bush, with the expectation you screw a pilot jet into the bottom of the carb within the float bowel area. This was quickly dropped for 4 strokes as the factories found getting the bikes to idle properly. the fix was the bush in the bottom of the hole where the pilot mixture screw sits.