Engine rebuild...

[tuareg_imp]

Thanks for the nice pictures, as you can tell you have our attention.
As a sympathetic audience we could do with some more information;
does the vibration happen when the engine is stationary and at what revs is it worse?
Is there a noticeable lack of drive and when the engine warms up are all four pipes getting hot at the same pace?

It happened from one second to the other, i wonder if the cylinders are contributing equally or if an injector is not working as it should

Found a picture of another cb1100 cylinder with cleaned pistons in front, notice the scraping on all 4 pistons/cyl's.



(click twice for larger image)
Not sure why pistons all score in the same place and I guess your cylinders were scored deeper?
And looking at where the scoring takes place ( well below the rings ) it makes me wonder if it's not something in the oil that gets splashed up to the cylinder walls that causes this?
I mean how does the carbon get past the rings unnoticed and settles below the rings to scrape away at both parts?
I'm sure we all feel the unbelievable misfortune that happened to you and wish for a fair outcome from Honda.

max, I think the scouring on the pistons is caused by the splash lubrication(or the lack of it) rather than carbon, probably caused by low oil level and/or low rpms. The scour area is typical for this kind of damage; it is where the pistons "lean" against the cylinder walls when bobbing up and down.
I had a similar experience in the past, not with a motorcycle engine but a marine diesel. It was a Magirus-Deutz air cooled 4-cyl. I installed the engine(which was 20 years old already) in my wooden fishing boat and sailed away. But I was in such a hurry to reach my home port I didn't bother with cooling air inlets and outlets, I just left the engine room lid open. But then because of the noise the engine makes(airhead, remember? ) I had to keep the rpms down. Fast forward 120 hours, I have trouble starting. When we opened up the top that was exactly what I'd seen.
Of course that engine was designed as a German workhorse, so the problem was solved with light sanding of cylinder walls and new rings... Definitely not the exercise recommended for a Honda
Ah, by the way, that engine is still operational I believe, must be 50+ years old by now. Oh boy, I massively drifted off subject...