Hi,
Since 2014 I note the frame and engine numbers from K0, K1, K2 on ebay ads. Originally it was to know the building date of my K2. So :
1 - The american bikes have the frame number ant building date indicated on the VIN plate, so I can deduce the building date (month / year) of a bike when the frame number comes between two VIN numbers. I also note real bikes and ad's from Bonhams and other sites.
2 - The first K0 did'nt have VIN plate but the "Sandcastonly" list allowed me to note the numbers...
And it works pretty well to detect the "matching numbers" as well.
A real example with this ebay ad :
https://www.ebay.com/itm/1969-Honda-CB/222893094739?hash=item33e576b753:g:WK8AAOSw2DBaspP7&vxp=mtrHere it is, in blue (frame #1001966, engine #1002074). The two previous one and the following two are from may 1969 (source Sandcastonly) so the "blue one" is from may 1969. You win !
05/69 1001774 E1001854
05/69 1001849 E1001884
05/69 1001966 E1002074 05/69 1001983 E1002005
05/69 1002136 E1002079
I have 308 K0, 174 K1 and 132 K2 recorded.
That's all folks !