That’s rough.I’ve heard of a few guys having issues with the Yamaha 824s, mostly around valve seizure and poor oil flow, especially if the motor runs hot or has long intervals between oil changes. But seized head bolts and completely trashed heads? That’s next level.
Sucks that Yamaha won’t stand behind it, especially with such low hours. You’re not the first I’ve seen swearing off both Yamaha engines and Bad Boy mowers after something like this.If you end up swapping, a lot of folks have had better luck dropping in a Kawasaki FX or Briggs Vanguard.