Nice scar, wobbly chain, self adjusting ( ratchet system? ) tension by the looks of the metal "can" on rear of chain area........up and down play and lift of chain from sprocket, how much??
If flywheel set to "T", do marks on cam sprocket line parallel with rocker cover gasket face on head??, or do they "lean back" quite a bit ??
Not that well up to date on the "modern" cb250, a different animal to the old faithful cb's.