I am currently rebuilding a set of 1978 CB550K4 carbs. (ie) The PD46C variation which I have a question regarding the change of the float level from the previous 1977 CB550K3 model of the PD46A carbs.
The 1978 K4 level is listed as 12.5mm float level setting, while the 1977 K3 level is 14.5mm, these are both are per the FSM as quoted here.
Is there a reason why Honda made this change between these models? If one of the past Honda techs on the forum has any insight I would be grateful. The 14.5 mm setting gets the float reasonably level in the set up, while 12.5mm leaves the float on a downward angle.
The only difference in the carb jetting between these two series is the slow speed idle jet. Which the 1977 K3 uses a #38 pilot, while the 1978 K4 uses a #42. Would the change of this jet size warrant a fuel level change in the bowls?
Since these are a bit of a bear to remove and rebuild, I am looking to get this right. Has anyone used one of these settings when rebuilding these carbs and what worked out for you?
