Back to the SohcCBs Tech Index....or back to "float height adjustment".

This is a 38 year old float gauge tool supplied by Honda to their dealer mechanics.  An ex dealer mechanic that worked for a Honda motorcycles dealership saw my site and sent me the image of his original float gauge that Honda to supplied to him and the other mechanics.

You can see above that the original tool fits in the indentations located in the center of the lip around the perimeter of the carb. This was the original float gauge tool made for the 1969 thru 1976 CB750.  The CV type carbs of 1977 and 1978 had no lip around the carb and were measured with a later tool from the gasket surface, but the early carbs were measured from the lip around the bottom of the carburetor body. See bottom for measured comparison.
You can see he sent me a photo of the float gauge tool being measured with a high quality dial caliper, in inches.  My caliper at the right has both inches and millimeters.  Both are set at a tad over 1 inch, and clearly 26 millimeters.