Im working with a set of NOS std cases. The bike is up and running but I made a big mistake and forgot to install a plug for the primary oil return while the motor was out and the oil pump was off. Now I have a threaded hole that’s hard to get to behind the oil pump and doesn’t seem to fit a 1/8 npt like the other oil holes on the case. Any idea what thread pitch that is? Options? Photos I found online to show the factory fitting and the hole location in question. The hole is just inboard of the oil pump.


Found image on eBay

 

I'm in the process of rebuilding a 65 pan and that hole is 1/8 pipe.. Original cases..