no luck still, didn't change the cam timing yet, switched to a 18x8 2 blades biela and only managed to get 6600-6700 rpm, even playing with ignition timing. I don't understand this lack of performance, and why before it peaked at 7200 rpm with biela 16x10 3 blades, giving good flight performances, and then never more. Engine got fully inspected and no issue found. On next weekend i will field test it as it is, will see if sailplane will get off water.