Need help identifying engine plug on the bottom of a '78

[cmills83]

Hi,

Im dusting off my CB after a few years in storage and trying to determine what Im missing in the below photo. Looks threaded down the middle and has a plastic (probably rubber at some point) o-ring. It doesn't appear to be leaking but would like to fix this

 

[hinksy]

That is were the neutral light screws in

 

[dirtdigger]

It is the neutral switch

 

[cmills83]

Oh ok, thanks!