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It would certainly help too know which area of the engine the noise is coming from.  By the way - is it running on all six cylinders? It is difficult to tell from the video, but the idle sure sounds rough.

Sorry you are experiencing so many setbacks with this bike, but your posts are frequently very entertaining and humorous!

I got them to lend me a stethoscope.
I started the engine and went checking different parts with the tip, the metallic noise that reaches my ears has me more lost than a cat in a garage.
-Now 
-it seems here ....
-no wait...
-on this side is heard louder...
-This other chime had not heard before...

In the end I focused my attention on the clutch pot, it was emitting a sound worthy of an Argentinean protesting from the balcony of his house with a saucepan and a metal spoon in his hand before the arrival of Milei to power.

I drained the oil from the crankcase and disassembled the clutch cover.

Everything seems to be in order, there is no play in any part, I disassemble the clutch discs without noticing anything unusual.

I reassemble everything disassembled so far, tighten the clutch cover screws.

I'm sitting on a small stool like the ones used by milkmen to milk their cows, while I tighten with my hands and arms outstretched the oil drain screw of the crankcase, my snout is right in front of the pickup, my mind lights up and I think .... 
Why not set the pickup back a few degrees? 
Starting from the idea that the noise of the engine is produced by an undue draft and the spark arrives before the detonation point...

I take off the protective cover of the pickup, delay a few millimeters the regulating plate and start the engine.
Really, it seems like a fucking miracle, the noise has almost completely disappeared.


I stop the engine and delay the ignition a little more, I start again.

The damn noise is not completely gone but it is much less audible.

I feel good, I celebrate by twisting the throttle, in a few seconds of euphoria I reach 7000 RPM and that's when a metallic screech makes me come back to reality, I immediately stop the engine.

My balls have fallen to the ground, my euphoria dissipates and escapes along with the smoke out the window.

I'm about to tell a neighbor to go fuck herself and yell at me from her house that it's not the time to make so much noise, but I bite my lip, tonight I've already exceeded my quota of bad blood.

Tomorrow, with the engine cold and unwilling, I will disassemble what I can to see the wreckage.

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I have empathy I'm still fighting issues on my 79, ignition. Got so bad I covered her and haven't even looked for weeks now. Someday I'll find new courage and try again.

But... I got to say, your prose makes me laugh. This one had me spewing diet coke all over my lap top..

"In the end I focused my attention on the clutch pot, it was emitting a sound worthy of an Argentinean protesting from the balcony of his house with a saucepan and a metal spoon in his hand before the arrival of Milei to power."

 

I don't like the sound I hear of the starter as it starts rotating the engine. Doesn't sound normal. Then once the engine starts there  is a metallic whirring sound overlapped with what sounds like a tight camchain whirring and then the tapping noise on acceleration. Way too many things going on at the same time.

My first concern is the noise at first starting. We've heard of lots of issues with the starter clutch coming loose and when it gets really  bad, it won't disengage from the starter which can cause the windings in the armature to explode.
then you heard a metallic screeching noise- did the engine come to a sudden stop, or did you stop it?
If you stopped it, then I would definitely check the starter and see if it's  intact. 
You need to deal with all these mechanical noises first before checking the ignition timing. The rattle on acceleration could be detonation but what I hear is more like an issue with one cylinder and detonation would be with more than one cylinder at the same time. Even if the timing was off 5 degrees advanced or retarded,  i doubt that you would hear detonation.

Tonight I went down to the garage without even having dessert after dinner, my children advise me to take a break with the fucking bike, what my wife says I don't even listen to, so we avoid arguments.

I disassemble the coils, remove the cover of the valve shafts, nothing is damaged.
I activate the starter motor, the engine turns without difficulty.
I remove the cover of the starter motor, the clutch mechanism works perfectly, with some slack but it does its function, the starter motor is a little hot after running it.
I take off the cover of the chain that drives the pickup and the shaft of the water pump, everything is fine.
I feel some slack in the timing chain, with my hand I can tighten the tensioner nut one more turn after releasing the locking mechanism.

I introduce the endoscopic camera through the opening of the timing chain, nothing strange can be seen, I introduce it under the crown that drives the starter clutch, I turn the crankshaft without seeing anything strange either.

Tomorrow I will disassemble the cover of the generator to introduce the camera and see if everything is correct.
I will filter the oil to see if there are metallic flakes.

I will order the cylinder compression tester again.

I owe the guy who lends me all these tools a couple of good old fashioned knife and fork breakfasts.

If nothing strange happens I will restart the engine to see what the fuck is wrong this time.



If I ever have to disassemble the engine block again, I will drain the fluids, apply a coat of wax to the paint, polish the chrome parts and park it in the living room between the fireplace and the grand piano, hoping one day to have grandchildren and be able to take Christmas pictures riding Christine.
Only I know how much I have spent on this useless piece of furniture.

I could never allow something mechanical to beat me. I would have to finish it to win, then either park it and stare at it, or if I was my father, grab 2 sticks of dynamite and blow it to smithereens just to teach it a lesson.

I was a licensed auto mechanic at one point in my life and made a really good wage working in that trade. During a mid life crisis, I bought a Porsche 928 basket case. Once I had the car, I needed a shop manual. Who knew the manual was 7 - 4" binders that would take up 3 feet of shelving. That car had 4 fuse panels, 3 relay panels and 2 computers. If any car put the screws to me, it was that Porsche. It was my Nemesis. I had to finish it just to keep my sanity. My greatest reward was finishing it since it was my greatest challenge and I'm a better man for doing so.
Don't give  up or give in KawaBCN. You've come too far.  Just remember- the guy that sold it to you gave up because it was too much for him so winning this challenge is a win over him. And let's  not forget that  it's a 45 year old bike with limited parts availability.  A win here is a real accomplishment.