So, this has gotten away from a carbs-only thread, I'll get back to those shortly.

A couple of other things to think about:

1. Since I'm already into the head and have the exhaust cam out and am waiting for shims to be delivered, I'm thinking this is a good time to address the broken exhaust stud. Are there any gotchas to taking the head off? Now would be an ideal time to pull the head and have a shop fix the broken stud. Other option is to wait until the bike is back together and have it fixed while on the bike.

2. I've a spare engine that appears to be in good shape, really clean. Previous owner told me that it has low miles, but low compression on #2 cylinder. How hard is it to test compression while the engine is out of the bike?

 

1, Of course there's a little more involved with taking the head off and replacing, but easier to do the stud (all depending if you need to drill it out)
2, Can use a drill on the crankshaft to turn it for the test on the spare engine as all other plugs will be out as well ( has it got oil in)

 

Spare engine and head stud repair will have to wait, as my shims came in. So, time to get the valves sorted and the carbs back on the bike.

One thing I noticed when looking at the pilot jets is that someone must have drilled them out. The 38S jets that are in the carbs have a really large hole through them (end to end), big enough to fit a paper clip through. (0.79 mm) I have a couple of spare 38S pilots, and the hole through the jet is half the size, 0.4 mm.

With pilot/idle jets drilled out, I assume i'll have to turn the a/f screw in a ways to keep the bike from running too rich at idle? Should I even bother trying with these pilots, or just order replacements?

 

Yes ,I would just order new, saves you having to adjust settings and gives you a firm base to move on

 

I knew that would be the answer before I even asked the question... Time to find some jets, will give it a go with the drilled out jets to find out how much of a difference the valve adjustments made...

I've found some 38S jets available via ebay, even some #40 from an F3, but no plain #38. If I understand this right, sticking with the #38 vs #38S (or #40) is the best route to go?

 

Saw these
https://www.ebay.co.uk/itm/Slow-Jet-...HrVaWf_7wn2yIQ

 

Good find. I found these stateside, ordered a bunch of them, may as well have spares... https://www.ebay.com/i/232629626587?chn=ps

 

New (to me) idle/slow jets arrived today in perfect shape, have to love ebay as a used parts warehouse...

Installed the jets, hooked everything back up, and she fired up almost immediately. Idle is nice and smooth, but I'll give the sync a go this weekend as well.

Thanks to all for the pointers and tips, I plan to make a post with what it took to get it going, and all of the fun along the way.

 

Awesome my friend m Glad you got the girl sorted out.

 

That would be good matey, may help others in the same position