Probably the top end due to no oil in the filter and a dry oil system. Mine hammered pretty bad when I did a top end this last fall. I actually shut it down after I herd it. Then crossed my fingers and started it back up. It lasted for probably 5 maybe 10 seconds at max. That is why a good engine assembly lube is required.
2003 Limited Edition Raptor
Kenz 720cc 11:1 stroker, +1 valves, Mega Cycle X-4 Cam, Sparks 6x Big Core, Keihin 35mm FCR's. 158 mains, 52 pilots, fuel screws 2 turns out.
F.A.S.T. Dune Ported 4mill, CPI Inframes, Keihin PWK33's, Direct Drive Lockup. 158 mians, CEL needles second clip, #48 pilots, air scews 2.0 turns out.