Tuesday I took the moped to work, but when driving home, it began to vibrate at high revs and it made some funny noises. 5KM later I was at the workshop, had a quick look if the flywheel nut might have come loose, but it didn't, so I thought it should be a clutch problem. After all these years of abuse, I finaly managed to break the engine.

Today I started disassembly by taking of the exhaust to have a look at the clutch, but to my surprise, it turned out to be as simple as a broken motormount bolt.

I had a new bolt, put it in, put the exhaust back on, started the bike, and the vibrations were gone, engine still in working order, dispite years of abuse.
This motor has almost no compression, you can hear the piston ratteling in the cylinderwall, it never gets new oil, at best the old stuff out of a race-engine, it gets overrevved, overheated with burnouts..... but I still can't get it to really break. Real Honda quality, no chinese parts.