4 cylinder YICS question

Hi my XJ700 air cooled ith YICS has been fouling spark plugs excessively with soot deposits from over-rich mixture. I've found 1 carb with a high fuel level and wondered if the YICS drillings in the cylinder head could be spreading the excess of fuel from this one carb across all 4 cylinders, making it appear that all 4 carbs are flooding? I've cleaned the YICS passageway and tested that all 4 air holes are clear with an air compressor

 

Possible but not likely unless raw fuel was getting in there. Have you taken your carbs to church of clean yet? Go check out the tech section behind that little xjforever doo-dad in the upper right side, there's a great section on carburetors that's written by the experienced and considered the bible by many.

Welcome to the XJ forums.

 

Well I would say otherwise, at least to a degree. The yics "shares" some of each carbs airflow with the other cylinders, so if it shares airflow, it will share mixture, rich or lean. Mostly though, the rich cylinder will be most rich, with the others just being richer than they would otherwise be. Only by analyzing all cylinders and adjusting one could you quantify how much...