I'm really pleased, that I've an worldwide network of experts and friends. Long story short: Bruno a friend from Portugal had a closer look at my stroker engine build video (www.youtube.com/watch?v=tBGVuvlaE1o). He noticed that we used the wrong main bearings because he already know's the difference from his own builds. The oil supply is different between the ZRP stroker and the stock crankshaft. For that reason main bearings with grooves must be used on all main bearings to secure the lubrication of the big end bearings. Like other forged crankshafts the ZRP crank is designed to supply one big end bearing from one main bearing - very basic but important information.