I discovered the carb needles on my 1976 CB550F were badly worn when I first started it after a restoration. It would start without the choke and blow greyish, rich smelling fumes. I tried the usual fix of dropping the needle to the last (top) position as it was already in the 4th position. This made no change at all. I checked the needles with a jeweler's eyepiece and found that all 4 were marked with striations all along them from top to bottom, presumably from rattling inside the emulsion tube due to excessive wear.
That's when I found that new needles are as rare as rocking horse crap, and I didn't want to use aftermarket ones.
As I have a few spare CB500 627B carb sets, I decided to swap the needles from these into my 069A carbs, along with their emulsion tubes (as they have slightly different hole sizes).
After a test run today, I'm very happy with the bike's performance and it doesn't run rich anymore.
My bike is totally stock other than a Delkevic 4 into1 exhaust system.
