@FridgeFreezer maybe it's too rich, I don't know it properly because at 1600 MSL is working good at 850 RPM, but I supose that is rich for altitud reason.
It's not that bad, maybe make some settings to keep it in an intermediate range.
I replaced them already twice, also all carb gaskets as well once.
It's true, for that reason it was not common, I didn't know if I was lacking any knowledge about it.
Thank you for your help.
Any other idea?