thanks for the tips
it was great until my father heard what i want to do.....he said the carbon bits falling will scratch the cylinder sides....any chance he might be right?

now if i am gonna try some thing....i ll go for the water.....i don't think i can find the other liquids easily, if some one had it, he probably don't now what it is, or mistake it for another thing.....i ll have to ask first though to see if they know of such things
now if the water didn't make it to the cylinder, it ll be trapped at the bottom of the intake manifold, right? is that a big problem

can i use one of the halls that brings vacuum to other things (like the one connected to the fuel regulation valve?

or is it too small, one can use the breather also???
or am i better leaving it to burn by its own??
still one thing...if it is a carbon build up, it would knock only when it is wormed up, is n't it? and it will be knocking all the time when it is worm, is n't it?? i am really not sure......it most of the time start knocking as soon the worm up cycle finishes (temp gauge still below 80) and i had plenty occasions when it worked very good when it is worm.