Here's a good link to fiche.
I notice on the piston assembly that the wrist pin clip is called out at 23mm which converts to .905"
This is much bigger than the part you have.
It must be something else.
If you look at the shift drum assembley there is a clip that measures 14mm. Could be this.
I also see this same clip on the kick start spindle.
Also check out the oil pump assembly. I see a small clip there. This might be an easy fix. I think the oil pump is accessible without splitting the case.