Plug/bung by final drive sprocket

[Murf]

Hi
I have to split my crankcases soon so wanted to check out the worn bung/plug that is by the final drive shaft. The bung is quite worn down as can be seen in the photo, so it looks like PO has tried to use a 530 O ring chain which is too wide, should be 530 normal chain.  I have looked in the parts manual and on cmsnl and this bung does not seem to be a listed part, this is often the case when Honda never considered the part would be needed.  So does anyone know anything about this or had the same problem. There is no leak from the bung so if it is quite thick maybe there is no problem.

[Bryanj]

91207374000 its on the gearbox page

[Murf]

Thanks
Yes I see it now, I was looking at the crankcase parts thinking it would be part of them, good to know I can get it and only £5 😄. It’s also in the seal kit they do at £19, I might go for that as I need some of those seals as well. 😄

[deltarider]

So yours is a CB550, right?