Probably from the starter clutch. If your not the original owner there is no way to verify that it hasn't been tore in to.
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.