For both HDs to crater, is that a design problem in those engines? I mean even considering they are heavily modified.
I think when they are exploring the extreme ends of performance, some bits may crater.
This happened often with the old British twins. The 33 seemed a tad quicker than the two Vance and Hynes bikes.
In the first race both factory bikes quit. I suspect they may have made changes ?? to the engine they swapped in, for race 2.
Note that the Moto3 Moto2 and MotoGP bikes rarely have engine failures. First race, Portugal 26 March.