Hello Nilzz! I've a niece & her family who live in the Netherlands.... I'd like to visit with them someday.... Your English is better than some of the Americans on this forum.... Short reach plugs don't necessarily mean "bad" head..... It was a bad batch of alloy that "melted" around the plug holes, etc., giving rise to "butterheads"..... I had one short reach and one long reach head on the bike, when I got it. It ran.....the same heads now match....long reach, or LK..... That subject will be covered later..... I've not heard of a 4th over...I thought it stopped at 3rd over..... But I DO know what you mean about German "dough".... In the States, these bikes are expensive to renovate.... Sounds like you have a basket of poisonous snakes there! Post some images!