Wondering if it even needs to be welded or if i can leave it go I thought maybe it could be left. Any ideas by the gurus on here that would know for sure if i can or cant would be greatly appreciated...
am i missing a trick but what is the problem? if it seals = it's good. rotary file is to clean it up and narrow the width down to the same as the rest of the casting.
My guess would be that that part of the casting is a crude "baffle"- there to stop oil being slung off the cam chain/sprocket going straight up into the 2nd crankcase vent tube which is directly above where that piece is (or was).
I'd try running as is after its cleaned up- if its getting too much oil in the frame/breather I'd go back to the original 1 breather style system as used on the 02/03s- or mill it out and get a piece welded into it.
But thats only a guess as for its existence- its definetly got nothing to do with rocker cover/head sealing .