remember the guy who has his 100 twin spit out a cylinder head? why dont you check the head bolts and the thread that was made on the crankcase and re tighten with locktie.

and the break in and cycles leave that for engines that don,t use piston rings, if your engine poops it will most likely do it on the plane even if you ran it 3 hours on a bench, thats just the way live is.

If I were U I would disasemble the engine and check all treads, the crank pin, and seals.