problem solved,i guess.Today i was replacing the gasket between the cylinder and the engine.Ideal moment for cleaning the powervalves(d**n,nasty stuff)and followd the intructions"top end rebuild".Everyting is back together now and works fine,but i dont remember that i find them in the same position this morning.Could it be that the previous owner misplaced them?(with the mark backwards)I tought that when i looked this morning,before the cleaning,that there was one exhaustport open when the valves are closed and when open,the second port comes free.Is that possible?I hope you can all read this(i speak better english than i wrote
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