I too am in the same position but mine are in bits so if it’ll help I can e-mail you some pictures so you’ll know what you are looking at.

My upper outer tubes are lightly pitted on the inside and I would not think that anything less than perfect would be reliable. I doubt there is a cost effective restoration process therefore you will need 1.625″ ID x 1.875″ OD hydraulic tube or at least solid drawn tube. In this metric age, (when did you last 0.25 an orange? – b****y metrication!!!), that might be a problem. It is the I’D’ that is important so if a larger O.D. can be found I can turn it down with little trouble. If you can source any I’d like to know by the way as I’ve not started looking yet. There is one other possibility that eliminates the sliding seal altogether but although I know the technology exists and is proven in other applications I have not been able to locate a manufacturer yet.

I understand that the Velocette Club can do the seals althought I do not know if the Dowtys used on Velocettes were exactly the same. I have also been told that not all Scott / Dowtys are the same either so check.

As a last resort there is a spring conversion I’m told.

And no I don’t know why I.D. shows as I’D’ I tried to change it and it wouldn’t!

David Elgar