Engine and frame numbers

[RDfella]

If we are suggesting the last number has been added, then they've all been 'added' because the nine is exactly the same as the six, meaning the same set of punches was used for all. The spacing is not perfect either, but we must remember these would have been stamped by hand, not machine. Whatever, the GA7A is the important bit and the A cannot have been added in there. I'm perfectly happy to say that all those numbers are original.

[JulianS]

The problem being that there were no 4 digit GA7A frame numbers.

[KiwiGF]

Maybe we should have a ‘sticky” thread on how to spot incorrect frame numbers, and how to date a frame and engine as it does come up a fair bit.

It seems there are many reasons why a number was not actually stamped by BSA, some legit (new frame or case fitted) others obviously not so legit 

I know some like to keep the numbers “secret” but engine numbers are generally obvious for all to see, and as far as I can tell frames have the same stamping “font” .......frame numbers are less visible.....but here is a selection of engine numbers from this era for comparison (and two from a bit earlier).

A “feature” not so easily replicated is that in some years the BSA letters and numbers seem to be different heights!

Edit: I’ve no reason to think any of these numbers are not legit, but you never know eh.

[RDfella]

Reason I made my earlier comment was because clearly the frame number we're discussing is of regular font. So either the whole number is genuine, or the whole number is fake. Clearly the next step is to compare with frame numbers either side, preferably in the same year, to see if it's a BSA font. I have several number / letter punches and none have the flourish the frame number pictured has.

[Joolstacho]

I seem to remember that replacement crankcases were not stamped by the factory, the retailer was supposed to do it, (presumably to match the original number). Sometimes it might not be done, or might be done incorrectly.
My SR was used as a grass tracker and ran something around 14:1 comp ratio, the seller told me it had replacement crankcases (not surprising!) - it has no numbers.

[KiwiGF]

Here are ‘two types if 2” I referred too earlier, I guess only one is “correct”!

[bikerbob]

As Julian says there were no 4 didgit numbers for the GA7A frames also he has a valid point about the shape of the letter A stamping, the only way to verify this is to go through the dating certifcate proceedure with the BSA Owners Club. There are a number of dodgy frames about, I remember a number of years ago I bought a BSA C12 in bits to restore and from the same person I bought a donor bike that was complete except for the seat, now the donor bike had no paperwork because when I checked the frame number someone many years ago had ground off the original frame number and had strangely restamped it with a BSA C15 number. Looking at that number it looked like a perfectly good stamped number except fot it being a C15 number, it was only when you scraped the paint off that you could see the grinding marks.

[Voldsgaard]

I do really appreciate your help guys.

My next step is to do the dating certificate procedure from the BSA owners club.

Thank you very much.


Niels.