B40 in a C15 frame?

[Stubaker58]

Hi All
I'm struggling to decide how best to progress my B40 towards a complete registered bike.
The frame and engine number do not match, there is no V5 and the frame number looks but butchered.

My options are (I think) a different frame with a clear number or registering the current frame as a reconstructed classic.

C15 frames being more abundant than the B40 variety I was wondering about the viability of this option?

Will the engine fit straight in? Chainline? Forks?

Any thoughts gratefully received.

[Spaceman]

I'd have to double check but I believe the frames are identical except in the way the front of the petrol tank is supported and how the head steady attaches to the fame. Either engine will fit.

I'm not an expert on this subject but I would have thought the current frame is unusable if the frame number has been butchered especially if it looks as though someone has done it to stop the frame from being identified.

[Stubaker58]

Thanks for that.
That is my thinking too about the number.  One day I'll learn and buy something that's right. 
The frames are certainly pretty similar, the B40 is a bit bigger in the tubing though.
Will having a B40 rather than a C15 engine complicate applying for a V5 though? It may be simpler to stick with a replacement B40 frame?

[Spaceman]

I am sure that going down the age-related registration route would be simpler with a B40 frame but may still be possible with a C15 frame. I'm sure an expert can advise. Presumably the number on the current frame has been ground off rather than just difficult to read?

[Rupert]

B40 engine will fit in a C15 frame but you need the Complete C15 frame with swinging arm and subframe and rear wheel.
B40 frame, subframe, swinging arm and rear wheel are different to C15 as the B40 has the engine offset by 3/8" to give a wider chainline.
Easiest solution is for you to keep your B40 frame.
If you send me your engine number I can probably find your original frame number, it may be the one you already have, albeit butchered.

[Stubaker58]

Thanks guys
It looks like the number has been ground off and a new one very badly stamped by someone with a stammer!

[Spaceman]

It's possible someone has replaced his B40 frame and then failed miserably to punch the old frame number properly on to the replacement. I had to do this on my C15 because the old frame was too bent but I have had a lot of practice using letter/number punches. If Rupert can provide the frame number corresponding to the engine number, it may be possible to convince yourself that is what the person was trying to stamp on to the frame. Even if you can't, it would probably still be ok just to use the frame number provided.