The annoying leak from the points housing has not completely gone away so today took a Look. Also had a Think - always dangerous . . .
Originally, leak due to points housing not compressing the gasket - I hadn't pushed the cam shaft bearings far enough in. So, on advice, loosened the cylinder head bolts and tapped the bearings.
But another problem was that the holes for the housing screws were poor - two of three housing screws would not tighten fully and the two holding the Boyer plate weren't too happy either. Got the village m/c engineer to helicoil them - all five.
Unfortunately, that appears to have introduced two new problems.
The first is that the holes he drilled are not accurately centred. If we were talking about normal bolts that might not be a problem, but the housing screws have a tapered head which fits conical recesses in the mounting. Having the holes slightly miss-aligned means they won't screw down fully. I have been thinking that this is why there is still an oil leak.
But taking the Boyer plate off today it was apparent that the oil is coming from one of the screws:
I wiped the oil away before taking the picture but that's where it's coming from. Which suggests to me that perhaps the helicoiling job has breached the cam box - this is the second problem. If the enlarged hole has breached the cambox, oil will leak and find it's way along the Boyer mounting screw. The spacer tube around the screw is full of oil and enough has collected in the housing to account for the leak. May be wishful thinking but there doesn't seem to be any oil coming from the gasket behind the housing.
And now a question for the XS experts.
Is there a way to repair the threaded holes and restore the cylinder head and cambox cover?
I have been thinking along the lines of taking it to an engineer, along with the points housing for reference, and getting them to drill out even further, fit metal plugs and then drill & tap - on correct centers this time - for the screws.
Another solution would be s/h cylinder head and cambox cover. But that would be hard to find in the UK, expensive, and even if the mounting holes are in good condition it is likely that a forty year-old cylinder head will have some other problems.
Thoughts & suggestions?