Frame cap - just checking

[lmg]

I have one of these frame caps/plugs/bungs/whatever (first picture) and just want to check how to mount it.

I am assuming I remove the centre bolt in this second picture, then insert the plug and bolt it back up. Just want to check that undoing the bolt wont cause any adverse affects on anything (hate for the engine to fall out ). And other than "a grunt" it wont need torquing back up?

 

[Bendy toy]

The centre hole on Pic 2 is for screwing in a small slide hammer to pull out the bearing mount. Just treat the inside with rust repellant and fit the cover with that centre screw. Job done.