Honda CB400 Four Primary Drive Chain

After 54,000 miles and 5 years of talking about it, I finally decided to replace the Primary Drive chain on my CB400/4. As you can see it was very loss,
Can’t say if this is the original from new or not but certainly looks like it.

[ITZEZ]

Did you separate the lower and upper cases to remove and replace it? Or you just unpinned a pin of the chain?