BSA Machine Numbering

20 Фев 2015 | Author: | Комментарии к записи BSA Machine Numbering отключены
BSA 500 SS Gold Star

BSA Machine Numbering System

BSA a system of letters and numbers for identification of their machines. information combined with the numbers book (coming should help you identify the and model of your machine.

Pre markings are based on listings to the Club but do NOT have any form of referencing, therefore there is no way of their accuracy. Post the listing are cross referenced by the books and by contemporary listings in books and dealer service where available. This referencing is available for most up to the closure of the factory.

However we are revising the pre 1930 lists we are cross referencing with which we have personally and verified. We need your to help us on this and request anybody who has pre 1930 BSA bikes to the machine dating officer Pollitt (address below) details of your machine and of the complete bike plus photos of the engine. All photos be returned.

BSAOC pre1930 Machine

As with all listings of this there will be mistakes. hopefully, they will be few and far

It should also be borne in that these listings are in BSA seasons. This ran, from the August in the previous year through to the factory down in at the end of the following July. the 1953 BSA season ran from 1952 through to July

Identifying your machine.

a word of caution to anybody a machine, particularly if it does not any documentation or proof of origin. If you are not then do not buy as mistakes can prove later. Remember buyer

If documentation is available then the details against the machine. On BSA’s the frame number is in the following places. It is always raised numbers are casting numbers.

Up until 1968 it is for the engine and frame number to be and where the frame is shared by models the codes start the smallest model e.g. all A models have A7 or A50 prefixes the exception of the Rocket Gold and Super Flash.

On the front top frame member by the front seat stay or by the head.

On the front down below or in front of the petrol The exception is the early Bantams the frame number is between the engine mounting plate. are usually faint and small.

By the head reinforcing plate or down tube. Some on the engine mounting plate, sometimes break and re-welding the stamping.

Usually on the front mounting lug.

Front mounting lug but the engine and frame are the same.

1971 oil in frame

BSA 500 SS Gold Star

Steering head stem. The oil in B-series are stamped on the propstand

Engine markings

Engine are easier to find usually by the mouth on the primary side. are the Bantams which could be on the front mounting point or behind the crankcase mouth.

is just a guide and will fit situations but frames were restamped by dealers if the original was and a replacement fitted. These be stamped anywhere and often not stamped at all!


Owners with model BSA’s can easily the month and year of their as the factory adopted a dating for frame and engine numbers for the season models.

As with all previous BSA seasons the year started after the shutdown in July so that models were those between August 1968 to July 1969. They however have some in stock so that it is possible a July model may be to either the or the next year’s specification.

The consisted of three parts, the as two letters giving month and respectively, the second was a five number and the third a model The engine and frame received the markings. After dating and many thousands of BSA’s we found that often a was built or shipped outside the given by the lettering system so should only be used as a guide to the year and month of machine.

The date letters are as follows :-

BSA 500 SS Gold Star
BSA 500 SS Gold Star


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