I donīt think that itīs a problem of plugs . I think that the original BP is one of the best . It didnīt matter if I had some issues on some BP plugs .
Anyway . A engine that stucks a lot , need some degrees more to widen the sleve . Yesterday I called a friend of me . He told me that I was right . My friend is a engine genius . Important is when you run in your engine in off throttle that the temperature is a litle bit higher . About 80-85 degrees .
And befor you fire up the engine , you have to preheat it with a heatgun .

I changed the conrod after the braekin . After about 2 liters . And if the engine stucked a lot I change the bearing too . For the first 5 literes I use a fuel with higher oil percentage

I polished the BP conrod and I find that it will last some longer . Round all edges.