I picked up a '92 550 that appears to have a factory sealed engine. It already has a 42mm carb, and the PO just put a PJS pipe on it before he sold it to me. I think the rev limiter has never been disconnected.

You're write-ups on the 550 makes the crank sound pretty fragile. I know it is due for low end seals at a minimum. I am planning to put a Coffman's Climax pipe and have group K lighten the flywheel and do a mild bump to the compression, but I'm at a loss on the internals. SBT rebuilt crank? New rings? New pistons? Is there a way to evaluate these thing if the hours are unknown? A compression test with a quality gauge will give a little insight as to the rings, but if it is really necessary to change pistons at 80 hrs then I might spend the money now.

And additional insights or recommendations would be appreciated.