So here's a new one. I was back home in Canada last week and took it upon myself to help get my dad's 1981 P200 back on the road after a long hiatus. Long story short, after many mishaps (including one where the old man hard seized the 3rd overbore version) I finally got the thing back together with a new cylinder and took it for a spin. After a couple miles the engine died in such a way that suggested a loss of spark -- it was sudden, and not like a seize at all. I tried kicking it over on the side of the road and found that there was little to no compression. Dang, I thought, I somehow screwed this up so badly that I holed the piston after only a few minutes' riding. But there was no sound of debris in there and so I pulled the head off to investigate. And then the attached happened.
What the hey? Has anyone seen this before?
I swear I torqued that thing down the right way and just the right amount. And I lapped it beforehand.