Hard to see the engine number, but here it is:
CX500 engine, 1980. After opening the engine case to borrow the oil pump, we found this:
Opening the back revealed an eaten plate:
An eaten crank plate, tensioner side:
Guide side:
Deeply gouged boss:
Below that, a slot had been cut:
Why the slot? At least two links were broken:
The chain was moving laterally as well, as evidenced by the polishing effect on the crank plate:
We pulled the gearbox to check it for metal particles:
There were plenty to be had across the gears:
If you’re intending on running an engine again which has had this sort of damage, the particles stuck to the gearbox cogs suggest it’s a good idea to remove it and clean it out thoroughly!