HUH, almost black ? ? ? [X(]

I thought if it was black that was really bad when its a new engine ? Its never been black. Apart from the ground running its never made a lot of smoke, especially in flight at full throttle. The only time Ive seen any real amount of smoke was transitioning from idle to full throttle whilst in flight or over the top of a loop, just before throttling back after the engine was loaded up going up into the loop.
I seem to recall reading that when new, it should be smokey for the first half dozen flights or so. Maybe today, with it a slightly greyish colour was OK, I did lean it a click or two before the first flight today but it didnt seem to be running as sweet today as other flights when the oil residue was a greenish colouring. Sort of surging occasionally at full throttle so I thought it was too lean when I saw the greyish colouring. After richening today it seemed much better at full throttle ? I also checked the clunk was in the right spot and not tucked under itself as I had been putting the trainer through its paces, ie multiple rolls, loops, outside loops and snaps or flick rolls, (full back stick and full left rudder gets its spinning round fairly quickly. (for a trainer anyway)
I think I need to lean out the low end mixture a touch maybe a 16th of a turn, the quick pinch test at full throttle shows no or tiny tiny gain in RPM and picking the plane up to a vertical attitude shows no gain or drop in RPM. After starting and running quickly to full throttle then back to idle, let it idle down to lowest RPM and remove glow ingnitor shows a small, maybe 50 to 100 RPM (guessing, no tach) drop only. I also noticed today that with a full tank, going to full throttle and quickly back to idle thers a tiny amount of fuel gets pushed back up the muffler bleed line, doesnt make it to the muffler, I just see it come up a bit, only at a freshly filled tank, so obviously the pressure is good to the tank, as the quick drop in pressure and flow rate of fuel from the tank has it pushing the fuel out the only other availble outlet.

Another question, how many little bubbles in the fuel line from needle to carb is bad ? I see the odd little tiny ones from time to time at idle but it doesnt seem to make any noticeable difference, at full throttle theres a few but again no noticable difference in performance. These are possibly coming from the tank but I cant see them in the green tubing only in the clear from needle to carb. Maybe I should change the tubing to ALL green then I wont see them and worry about them.