After much reviewing of many sources and no help from Honda, the best that can be gleaned is based on the following bits and pieces.
- Difficulty Level:
An Australian site gives this explanation:-
So from that , their surmise is that the first digit denotes year of manufacture.
However we have no proof that January was the change point, many makers changing their model year in October / November, so that stock is in the showrooms for January.
I have also found this page:-
This infers that the American understanding is that there is a year's disparity with the Australian numbers.
Now to actual experience, with a sadly incomplete list of cars owned by myself and other close acquaintances, I have collated the following:-
In chassis number sequence
1052xxx registered 05.07.74
1198xxx registered 09.04.75
2317xxx registered unknown
2367xxx registered unknown
4038xxx registered 02.07.76
4095xxx registered 10.08.77
6084xxx registered 02.08.78
7081xxx registered 01.08.79
From my involvement of carrying out the pre-delivery inspection of the first cars into a motorcycle dealer in 1972, I am certain that the Australian list suits UK and Aus markets, I am pretty certain that there was an 18-month ''year one'' slot , with the first cars coming into the UK before the 1972 public launch at the Earl's Court, London motor show, meaning that the lead stock must have been built in 1971, shown to the dealers around mid '72 to enable them to sort out their showrooms. sadly some dealers were not able to meet the image, being back-street garage. Some handy parts finds have been made in the lofts of one or two over here in the past by assiduous members.