Varadero 125 sudden noise and loss of power - got video

[Leo]

Hi folks, we got a problem and hope someone have an idea...

At the rev limiter junior suddenly lost lots of power and got a noise from his 2011 Vara 125. After bringing it home on a trailer we started it and took a video, both pipes get warm so it runs on both, but I think maybe something in the valve train has come loose, what do you guys think?

[Lemonwizard]

Interesting. This is almost the same noise that my 125 had before I took the engine apart. Turned out the camshafts and rocker arms were trashed; deep grooves, discolouring. The valve themselves seemed fine, although with quite a bit of carbon buildup.
Currently trying to find reasonably priced replacement parts...

10500 miles, model from 2003 I think.

edit:
I think the first step would be to drain the oil and see if there's any debris in there.
After that I'd look at the timing chain tensioner. Look up online how to check it, there is lots of good and easily digestible information on this topic on the net. They're relatively easy to access and if I recall correctly you can tension them manually with a flat screwdriver. Don't worry about reusing the old gasket for testing purposes, and if it doesn't leak simply don't replace it imo.
These are both things you can do at home. Taking the engine apart will of course require much more effort.