I have a CB77 with a marginally higher serial number that was first registered in 1966 so yours probably was too. My wiring harness tag reads '1965' as well but I think they date the manufacture of the harness. Keep in mind that Honda did not use model years at the time.

It might be possible but it would be very awkward. The problem is that you need to open up enough space to remove the top cover and I expect that just dropping the engine is the best way to do that.

Oops.

Give this a try.

https://drive.google.com/drive/folders/ ... sp=sharing

Here's a screen shot from a parts manual. I have no information beyond this.

I've collected manuals for CB77s and others on Google drive, some of which is 'recent'.

[...]
I've not shared the whole directory before so let me know if there's a permission problem.

I don't know what the going price is for bikes of this era but I doubt it's more than a few thousand for one that is in good condition, works and is licenceable. I'm sure many would agree that taking a bike that doesn't run and isn't clearly all there, from beginning to end will cost a lot of time ...

As far as I know, yes. Here is some documentation. The Owner's Manual (link #4) has the best description.

https://drive.google.com/file/d/1Gh2XI1b7Vyfv2Qao1UsQNMaN4aeOYron/view?usp=drive_link
https://drive.google.com/file/d/1R_WmLWuC3bnfE2dzb4NLtS4xokTC3R2h/view?usp=drive_link
https://drive.google ...