I see either dirt, debris or to close on the bearing to crankshaft clearances in the center of that bearing I like more clearances on the bearings to crankshaft than your using, to tight is way worse on a race motor than loose. Try having the crank ground down another .001 and try that, .0025 or looser on all of the bearings, rods and mains (all of my motors end up with .003+ rod and main bearing clearances)