Not happy.

My guess is that the threaded end was 10mm?

I'd make a drillguide for that. A piece of tubing that's a snug fit over the exposed shoulder. Another piece of tubing fit snug inside that, with the drillbit's ID, perhaps 7mm, for tapping to 8mm?

WER...I have little to no equipment. Nor do I have room for any of it at this point. Nor am I very skilled either. Not sure what size the threaded end was, I'll look for a welding shop in the area.
Pete and everyone else. Thank you!
I'll post an update when I have one.

Good - thanks. This isn't a fun problem to have but it is a pretty common issue when working on old equipment / vehicles and so the experts in your area will be able to get it sorted out.

Pete

Check the other side, it should be the same size as the one you broke off. This is a perfect example of why nothing on a bike should be assembled dry. Bikes are exposed to the elements and this is what's going to happen to all the fasteners if you don't put some anti-seize or even some grease on them during assembly. Even if it's not a moving part, it needs to be assembled "wet".

Quasi-update: I have buddy who welds and is willing to take a look at my bike. gggGary said to remove all TCI prior to any arc welding. I have a 77, I have points. That being said; If my bike is going to get welded, what precautions do I need to take prior to that happening? Sorry, I just don't have any welding experience, so I want to be sure I don't do any preventable damage. (that I haven't done already)

Take out the battery

thank you angus !
.....
Bob......

So, not wanting to leave an unfinished thread. I have the following update. Although my buddy can weld and fix things, he decided that he'd just drill and tap the shoulder bolt and add a new one. I dropped my bike off at his shop and he took care of it for me. Pretty sure his dad did most of the work. I asked for documentation, but I didn't get as much as I'd liked to have. this is after picture of the bolt being drilled out.
this is the bolt inside the fender.
this is what the outside looks like now.


I kept the brakcet for the backrest because I like the wider turn signals. I am not sure if I like it yet or not, but it looks a lot better IMO than it did before.

Hi Mackels: I think it looks good - not an easy fix, but it's done. The only person likely to notice it is you.

Cheers,

Pete