I don't think it's correct to say "There are loads of original bikes". In terms of early-war specification machines, I can only think of about a dozen, even interpreting 'original' at its most liberal.

There are a number of things on this bike which are not really good practice. The odd small capacity silencer will be either noisy or restrictive, the mudguards are a horrible radius and run too close to the tyres and the odd homemade headlamp brackets are just waiting to fracture.

If the engine and frame numbers show this to have been either a British Army (BEF) or Dutch Government machine then I think it would certainly be worth putting it back to an original specification. It won't be cheap to do though, especially if it turns out to need an MT1130.

That so many posters on a specialist forum such as this one are not interested in whether it is a 1939 machine or 1945 and tend to think that all K and WM20s are 'common' and by implication the same, suggests to me that there are plenty of reasons to put another accurate year-specific model back on the scene.

Personally, I have an obsession with 1930s motorcycles and regard anything which detracts from the period illusion as a negetive point.

What I meant, but didn't say, is that there are loads of bikes that are meant to look original. This isn't by any stretch a hideous chopper and I'd just alter the odd problematic part and leave it alone. But then Daz and I have founded "The leave it alone [and just ride it] club". He has a 30's frame 20" wheels handchange tank and a '46 Norton ohv engine and no lights. I have left the demob paint on my 16H and just fixed the lights [or rather Daz did] and sourced and fitted an original field stand and sump guard. I just like my bikes to work first of all. I like the patina on old bikes. Though where patina finishes and rust starts is a moot point.....

email (option): j@clogmaker.co.uk

Thank for al those good advice but it is not my bike but from a good frend. He ask me to make it a runner and not an original BSA because this bike have a story to tel. This is my M20 and i found it in a barn . I also wil keep it as i found it and i let him see my M20 he says beautiful but not my one.You onley wil not know wath i must do to make it a runner. I let you know !