Just found that the airbox oil drain pipe was cracked and disconected - the one that is supposed to be under the airbox, at its front and center, near the stepper... Obviously, thats why It never had oil in it to be drained by removing the plug at it low end. So, as the pipe was con connected, air was getting in the airbox from the open hole, lots of air and dust, as much as it could through this hole to develop (on the hole) the same pressure drop as the filter. This airflow, not only brought dust in, also did not alow the oil to get out. So dust and oil, was sucked to the throtles, valves, and pistons. Some days ago I bought a cheap android endoscope, took a look with this, my intace valves and my piston tops have a glosy black layer of deposits... Crap. Took out and cleaned the throttles, next step to use whatever spray cleaner i can find, then cleaning additive in the fuel, hopefuly, sometime, the deposites will be removed a bit...