“But in 80 degrees temps after warm-up and 4-5 miles at 65 or more on flat ground it starts pinging at even the hint of an incline even without any throttle movement and dropping out of a pre-programmed switched "advanced" curve to a WOT curve wouldn't help it at all.”
At that time, pull over and use your WD40 with the tube attached, to carefully spray the intake flanges from the right side of the bike so as not to allow spray into the a/c. If it’s lean due to intake leak, rpms will increase as soon as the flanges get sprayed. No change in rpms? No intake leak.
Bob

 

seems you've done alot trying to rid the carb of this issue...and one can learn a lot from this kind of tuning work ...but just some food for thought ...if it ran as well as you say ..."years ago" ...
you could be seeing the influences of ethanol fuels ...with the difference mixes of this at difference times of the year ...this stuff is **** for gasoline ...try a couple tanks of the highest octane non ethanol fuel you can find ....
good luck

 

Yeah, I grew up in the petroleum business so I've seen well over half a century of changes, some good (engine oil/lubricants) others not so good (fuel). I ran only leaded fuel until it disappeared. Around here 90 e-free is scarce and premium e-free even more so, and priced .50 - 1.00 over premium e-10. Doing a lot of traveling, I've kept it near stock over the years so I could run about "whatever," knowing fresh regular is better than stale premium. Thru this issue I've run only premium and even tried one tank, heavily dosed with tetraethyl.

I think I've chased this problem riding, messing with timing and carb setting long enough to feel confident it's been an intermittent air leak that changes with engine and ambient temps (and many thanks to those who have offered support of that guess). It's an '87 that I switched to a (used) CV 15 years ago and suspect over time and tear downs, cleaning the intake so many times has worn it down in the carb bung and the spigots are tapered, rather than square with the with the inside bore. A couple of used one's I've bought look a little better but still don't seem to seal well.

The new manifold came in a day early and looks SO MUCH better than what I have. I'll post photos and specs of the intakes when I get it back together and road tested. I knew there was an intake valve seal slightly leaking but now it's slobbering, so I'm going to fix that while the tank is off. I've done it before with a cut-out socket, long flat pry bar and lots of patience but wimped out and ordered the special on-bike valve tool that will be in Monday night. So I hope to have it done and road tested by Wednesday night, if the weather forecast is anywhere correct.

 

New (reproduction) intake was the fix.
The others looked usable but for lack of better description, were slightly tapered in places and gently worn in a ripple in areas on the spigots, and somewhat wallowed in the bung. Not by much, but obviously enough to cause grief. Just had me bluffed with absolutely none of the typical symptoms of an intake leak before or after any time I resealed it.

The new one measured identical (1.93) in the bung and smaller on the spigots (1.810 vs 1.790)? but were near perfect round and not tapered at all. I generally use HD gaskets but did use the James "blue" o-rings with the lip this time, and OEM for the grommet. It all snugged up without any holding or prying toward center and the carb is perfectly centered in the manifold. Happy times!

It's 25 degrees cooler weather now and I may have to come off the timing next summer but for now, I'm able to run 35 BTC with only the slightest, occasional ping at sustained high speed and no issues at 32 BTC. I'll tinker with the advance curves later and call it good.

Many thanks for all the ideas, reminders and info. I sincerely appreciate it

 

For those who put up with my desperation thru this issue I felt obliged to follow up with the end of story.

Without going thru it all again, mine still wasn't right at all. Started detonating again in 55 degrees. Long and short, I found the result and the remaining puzzle piece. Apparently 7K this summer with the intermittent pinging/adjusting/etc. I cooked my piston tops.

They call it flash ash. Looks like carbon but it's actually the aluminum cooking. It flakes off and burns. Nothing will correct it once it gets gets so far gone, until a hole appears.

Decided to go into it and see what the heck and still was head scratching. Skirts, lands, bore all good so I was gonna clean, re-ring and maybe do the valves. I didn't have a clue till I started cleaning off the carbon from the piston domes. They look like you melted solder on them. With a butane mini torch, you can run it across the (clean) piston crown and it'll flake up a tiny pieces that light up into a cinder. That's why nothing I did had a positive effect for so long. Thru many miles of thinking I had it whipped only to have it reappear, the result of the all various minor issues I had, became the actual problem. It puts a bold exclamation point to the text - ".... severe engine damage may result..."

Bit of advice - if you have a spark that doesn't appear with any regularity and seemingly for no reason, find out the cause immediately and if you've set a nosecone ignition by the "static timing method," verify it with a timing light. Mine was 2.5 degrees set precisely by the book. And just because you put new seals on the manifold doesn't mean you fixed an intake leak, or if you did, it that may change with a few heat cycles.

Thanks again. Merry Christmas

 

Have you verified that the tank is vented properly and that your not draining your float bowl? A poorly vented tank would take a bit of riding time to get to the point where your bowl level is getting low!!!