Part identification

[Paustin055]

I need some help identifying a part. I tore apart a huasheng 49cc 4 stroke because it had no power and was knocking. It turned out the rod bolts had loosened up. Ordered a new rod but Now the engine is almost completely disassembled. I every part makes sense as to where it goes except for this one part. It seems to resemble a washer. If I had to guess I would say it probably sits on the cam shaft roller. I’ve attached a few images. Thank you, all.

 

[Paustin055]

I should also add that I’m following a manual I found for the Honda gxh50. Obviously not perfect but it’s the best I can do. This part doesn’t seem to show up in that manual, or I’ve missed it.