Speaking again about these dots. This is now the second time I've seen this and it relates to the "DOT" being found on the carb rack. My VIN11970 has a blue dot on one of the outer carbs. I had forgotten about it and did not even link the engine dot and these carb dots. I have now come to the realisation that they are one and the same. This dot is exactly the same as is on my K0 and is seen on a K0 carb set for sale on eBay
http://cgi.ebay.com.au/CB-CB750-CB750K0-CARBS-K0-CARBS-CB750-CARBURETORS-/160573584677?pt=Motorcycles_Parts_Accessories&hash=item2562ee7525 (http://cgi.ebay.com.au/CB-CB750-CB750K0-CARBS-K0-CARBS-CB750-CARBURETORS-/160573584677?pt=Motorcycles_Parts_Accessories&hash=item2562ee7525)
Methinks this is interesting and still a mystery.
(http://cb750k0only.com/coppermine/albums/userpics/10003/_28KGrHqZ2C21k4E2ERPHGOnBNp29nv28kBw7E7E_125B15D.jpg)