Hello guys. First of all, my english is not the best, sorry for it. So i'm after the valve clearance adjustment. (set to 0.05)  I'm annoyed by the left side ticking because nothing like this in the right side. How is that possible and overall is this healthy engine sound or not? I fixed everything on the bike, so i want to sure about it's fine or not.

VIDEO#1: https://youtube.com/shorts/jgBNb0kYbcE
VIDEO#2: https://youtube.com/shorts/uikPMlghsuk
VIDEO#3: https://youtube.com/shorts/iBoYftLLs8Q

Cam drift. Move the cam shafts side ways. It will clack from that even if valves are in spec. BTW in spec valves also are audible.
That's why "click and clack" the tappet brothers was a running punch line on US radio for 50 yrs.
Cool.
Buddha.

If it's moving why is that hearable only from the left side? I've heard a couple engine from videos where the shaft was moving, but there was a deeper sound instead of such a high frequency. if I understand correctly then the valves should have this sound, so they are fine. So am i have to accept it's sound like this and stop worrying about it?

I found a video that was made shortly after the purchase (last October) and I can't hear that ticking here.  Plus, one of my exhaust valve clearance here was larger than 0.08. (This is just like the other videos made with a warm engine.)

Video: https://youtu.be/bDHZ2fFthmo

I really dont know why it taps more on the left and also they only sim it on the left from the factory.
Open the thing and look if you have a shim on the end of the cam shaft. If you do, well pull it out check if you can mic it or if it has a number on it and its either 1.0 mm, 1.1 mm or 1.2mm - if you can get the number off it, see if there's enough clearance with a feeler guage to get to the next size up without it binding.

My observation, around .3mm you will hear it, and the thinnest shim they made, and they only made it when the wonderful made in spain quality took over - 1.0mm. So you're likely 1 shim too thin, cos likely you had one already being an 04 (spain bike) but if that noise was in an 89-00 bike, you're screwed till you run it for 300K miles, cos at 50K I barely had .3mm. I had to weld up material on the side of the cam tower and micro grind it down etc. Cos no shims were ever installed in the 89-00, in fact that shim wasn't even invented till 04.

That sound is as annoying as Kamala's laugh/cackle but it cannot be fixed for the 89-00 bike much like Kamala and I doubt it hurts anything. Just off idle and usually left front is where you hear it. In mine the left exhaust was the only location I had to do that weld and grind job.

Cool.
Buddha.

I will check it tomorrow. Thank you very much for your help.

In the first video I notice that there is oil at the base gasket on the left side of the block. Is it possible that the base gasket is leaking?

Not likely.  Not long ago, I took off the generator side deck, to check a few things.  It's probably from there but I'll clean it up and see if it leaks.