INTRODUCTION
As with all listings of this type there will be mistakes. However, hopefully, they will be few and far between.
It should also be borne in mind that these listings are given in BSA seasons. This ran, generally from the August in the previous calendar year through to the factory shut down in at the end of the following July. Therefore the 1953 BSA season ran from August 1952 through to July 1953.
Identifying your machine.
First, a word of caution to anybody buying a machine, particularly if it does not have any documentation or proof of origin. If you are not satisfied then do not buy as mistakes can prove expensive later. Remember buyer beware.
If documentation is available then check the details against the machine. On most BSA's the frame number is located in the following places. It is always stamped, raised numbers are casting part numbers. Up until 1968 it is rare for the engine and frame number to be identical and where the frame is shared by several models the codes start with the smallest model e.g. all A series models have A7 or A50 prefixes with the exception of the Rocket Gold Star and Super Flash.
Pre war
On the front top frame member either by the front seat stay or by
the steering head.
1950's
On the front down tube below or in front of the petrol tank. The exception
is the early Bantams where the frame number is between the front engine
mounting plate. These are usually faint and small.
1960-65
By the steering head reinforcing plate or front down tube. Some Bantams
on the engine mounting plate, these sometimes break and re-welding obliterates
the stamping.
1965-1968
Usually on the front engine mounting lug.
1968 onwards
Front engine mounting lug but the engine and frame numbers are the
same.
1971 oil in frame models
Steering head stem. The oil in frame B-series are stamped on the propstand
bracket
Engine markings
Engine numbers are easier to find usually by the crankcase mouth on the primary side. Exceptions are the Bantams which could be stamped on the front mounting point or just behind the crankcase mouth.
This is just a guide and will fit most situations but frames were legitimately restamped by dealers if the original was damaged and a replacement fitted. These could be stamped anywhere and often were not stamped at all!
IDENTIFYING ENGINE AND FRAME NUMBERS 1969 SEASON ONWARDS
Owners with late model BSA's can easily identify the month and year of their machine as the factory adopted a dating system for frame and engine numbers for the 1969 season models.
As with all previous BSA seasons the model year started after the factory shutdown in July so that 1969 models were those made between August 1968 through to July 1969. They would however have some machines in stock so that it is possible that a July model may be to either the previous or the next year's specification.
The code consisted of three parts, the first as two letters giving month and year respectively, the second was a five digit number and the third a model code. The engine and frame received the same markings. After dating and identifying many thousands of BSA's we have found that often a bike was built or shipped outside the dates given by the lettering system so this should only be used as a rough guide to the year and month of your machine.
