Capt'n you are genius.

I looked through my carb and there was a brass cap. It was on the metering site and looks like above the main jet. I popped it out (it was easier than I thought using some metal screw (about 4.5mm dia) and there was a fine mesh screen under it. The screen looked clean but I couldn't see a light through it (I used flashlight inside the carb throat). So I took the screen out - it was clean, but I still couldn't see the light through the main jet. 0.3mm wire fit very nicely into it and using it i pushed out something that was inside the jet. After that I was able to the light (I mean the flashlight, not the "light in the tunnel"). Then I assembled everything together and try to run the engine.

Now there is no problem - engine is running great. There is a weired transition that is, when I kick the throttle from idle to wide open then engine hesitates for a while. Then running full throttle it looks like it takes to much fuel from the idle jet as when i close it rapidly it gets slightly rich and after a second or two it smooths it's idle. Moving throttle slowly doesn't create an issue. I'm afraid my "modification to the metering spring is showing up. I'm going to replace the spring with the new one and try it again.

Anyway the engine is running fine with this carb. I'm getting close to the point where I want to be.