Link is working for me now Steve, good write-up.
It's a bit of a fallacy that all old Brit bikes leak oil. Admittedly they did all seem to back in the day, but people forget they had a primary purpose as a get-to-work commuter workhorse, and were quite often a family's only mode of transport. I don't suppose anyone expected them to be future 'classics' back then. Not everyone was maintenance-savvy, and a lot were neglected. Vertical split cases were asking for trouble from the start
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Nowadays with modern materials and sealants you can get your old twin oiltight (which is more than I can say for some CBs I've owned!). Electricals are easily upgraded too.