If the other cylinders are so good, I hope what you find is just a minimally broken ring on #5. That way you don't have to do cylinder sleeves or even take out the other pistons. I know you like to do complete overhauls, but this may be a case of minimal parts - but a lot of labor.

It sure would be nice to fix the engine without having to strip it down completely and sending it off for a resleeve. Just drop the crank and pull out the #5 piston. That should tell the story.

Ken300D