167fml oil leak on stater side

[e30boy]

Hello I’m new to the forums I recently got 3 167fml Atv all had oil in the stater and no spark I thought to myself no problem I’ll get a new main seal and I’ll be good to go but today when the seals arrived I went to clean up all the oil and found a hole on the casing about the side of half a quarter (I’ll post pictures) i noticed all 3 of the had them so I don’t think it’s not supposed to be there because they roughly all have the same shape and some even have like what looks to be a molding around it like it’s meant to be there the hole is at the bottom of the casing right on top of where the hole for the oil cooler lines go all the bikes where from different owners any ideas the oil is coming out from there not from the main seal