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Discussion Starter · #1 ·
i've got a 1968 BSA 650 but i can't figure out the model, theres no vin (that i can find) on the motor and it doesnt look like its been grinded off. the ownership says that the vin is A6FXXXX but i can't find that online.

is it possible that its an aftermarket crankcase?
 

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You should have the frame vin on the forward motor mounts, take some pics of the left side of the case right below the barrell, that should allso be where the motor numbers are.

You might have factory replacement cases....... There are no aftermarket cases for BSA's.

.....Roach.
 

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Discussion Starter · #6 ·
Scavenger, my frame is a '57 plunger and no there are no numbers under the barrels but there is a logo on the back of the motor under them, its a small oval with something in the center but im not sure what, i can't get a good look at it because the bikes together
 

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a65f? or a6f? look close as the stampings were done by drunk teenagers and gorillas high on paint thinner that escaped from zoos.

I think you are looking at a 1968 A65 Firebird 650cc model if your first set of numbers are even close.

here is a close up of the vin number area you should be looking at on the engine of a a65 unit construction BSA engine.

 

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Here's a couple pics. The first one, engine and frame numbers. I know you said you don't have any engine numbers. Look closely at your surface where the numbers should be. I'm talking good lighting and a magnifying glass. Does the surface look exactly like the cast surface elsewhere on the cases? BSA sometimes put periods or dots in the numbers and these got pretty deep. Is there any sign of those left? The original numbers for a '68 Firebird Scrambler would start with A65FB, the B indicating 1968. Those numbers would be on both the frame and the engine.

It's possible (but not likely) that you have a set of replacement cases. Dealers who rebuilt engines with replacement cases were supposed to stamp the numbers back into them, but they didn't always. (Same with replacement frames, and it's not as uncommon to find an OIF frame unstamped. A lot of those were replaced under warranty.)

The frame numbers in the first pic, a late '66 Lightning, were just stamped into the frame lug at the front motor mount. (BSA began using matching numbers in early calendar 1966, which was about the middle of the production year.) Later on, the frame lug was modified to have a flat pad. (see the second pic, a '69 Lightning with the numbering system BSA started using in the middle of that production year. The '69 and newer BSA twins also had the engine number on a raised pad, with little BSA logos lightly etched in the surface. Much harder to fake.) The third pic shows a frame number from '65. The '62-'65 unit twins had the frame numbers up closer to the neck and they all started with A50 regardless if the engine was an A50 or an A65. Those engine and frame numbers did not match. OIF frames (not shown) had the numbers back up by the neck too.

If your frame has no numbers, either it's an aftermarket frame, (pics would help, you must know someone with a camera.) or it's a stock frame with the numbers removed. Again, look really close at the areas where the numbers should be. If you see any evidence that the numbers, engine or frame, have been removed, I would take it back where I got it, explain to the guy he can buy it back or explain to the police why he sold you a motorcycle with altered numbers.





 

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Discussion Starter · #11 · (Edited)
yes scavenger that is what my frame looks like and after reading about the unstamped replacement cases i'm convinced thats what i've got, as for the ownership, i'm wondering if someone copied it down wrong

also i don't know if this means anything but my case isn't smooth, there's a seem that goes from the barrels to the side cases
 

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I bet there is a number under the black paint on the LEFT side of the engine case right under the barrels. I have seen shallow ass stampings on some bsa bikes My frame number is so shallow that a coat of primer obscures it 90% and one coat of paint covers it completly.

If that is the high temp paint that you buy at home depot for cast iron stoves then I can almost garantee that is where it will be.
 

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take blue painters tape and tape off the area where the numbers should be and then take the spray paint remover from home depot and spray some into a glass jar or bowl (OUTSIDE) and then brush it on the area you want to remove paint.
 
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