TOPIC:

How effective are the '82+ rubber engine mounts in reducing vibration compared to the solid engine mounts on the early bikes? Not sure if it matters, but I'm planning to install an 800cc kit in the engine and I'm not a fan of engine vibration.

Is the engine different or is the mount change limited to the bolt-on hardware and frame? I'm contemplating a retro fit assuming it's a feasible update.

The KZ650/750 series engines are pretty smooth. The 750 engine cases are the same as the 650 cases. The rubber mounts put on by Kawasaki simply replaced the solid mounts. It's been my experience with rubber mounts is they don't help unless they are on something that really vibrates like a V twin.