Well, what delights will we find under here?
Since I have not been able to shift the head, despite undoing all the fasteners (no I didn't miss any) I have decided to attempt to remove the barrel & head together and biff the head off the barrel using a block of wood from underneath.
Thanks to the ever-helpful Brenton Roy for that most excellent suggestion!!
The only challenge is that now I must undo all the cylinder base flange fasteners, several of which are inaccessible due to the dynamo and the timing cover. So, off with the timing cover! Unfortunately my imperial hex keys were not at home - so I had to wait a little while. It's interesting that someone has fitted a set of cap head screws to this engine, so it's likely that someone has been in here before - which I guess is almost inevitable on a 60 year old machine.
However, it comes off very easily, apparently with no stripped threads, though there is a quite a lot of Red Hermetite about.
Here's what I found:
Nothing too appalling at first glance. Everything in it's proper place, nothing mangled, the chain looks good and the tensioner is all there.
It's quite dark though. Is this evidence of a lot of blow-by I wonder?
Looking a bit closer, there is quite a bit of wear where the chain tensioner bears on the case - but this is probably normal and inevitable since the blade is free to flex at this end and the chain tension forces the blade against the soft aluminium case.
I'm not too worried about that.
But see what is missing? I didn't remove the nut on the end of the dynamo drive shaft! It's gone! Thankfully, unless it is stuck to the inside of the timing cover (I haven't looked yet) it must have been lost last time the engine was apart. There doesn't appear to be any damage from it flying about inside.
This is a bit peculiar - the tab washers for the oil pump haven't been bent up.
The alloy block and the two plungers are free - we will have to see what tolerances are specified for these parts.
Next stop we need to figure out how to time the engine so we can put it back together. Then it is dynamo off, oil pump off & we will attempt to remove the barrel What fun! I might do some polishing first through, so I can clear the bench of the rocker covers and timing case.