establishing #4 carbs settings

a question that's been plaguing me is, how is carb4's settings established? I assume that mother Honda sets up #4 on some hi tech test bench in a process that's so closely guarded that meer mortals are excluded from the room. all well n good, until some backyard hobbyist detunes the standard. is the only fix is to remove it and sent it back to it's birth place?

I suppose all you have to do is tune it by the "lean drop" method and let it stand as the benchmark for the other three carbs. Only #1, #2, and #3 are adjustable in relationship to #4. Each one is adjustable using the lean drop method. If they have been "detuned" then all should be gone through and adjusted, then use the idle speed to make them all pull the same.

Checks with an emission sniffer in all 4 exhaust manifolds* and/or Colortune might also be helpful to restore the proper idle-mix again...
(* post '96 models do have M6 bolts in the horizontal parts of the downpipes)