What does a rebuilt motor mean?

Answer 1

It means that the engine was rebuilt to make sure everything would work again in spec.

And that means this: to hone (make them round again) the cylinder walls; pistons, replace the ones as needed, if not all of them, (pistons-that's were the cyclinders come in... pistons go up and down cylinder walls)((when a rebuilt is made you have to make sure this is really correct or you will get an oil burn out of the exaust), mill (make sure they are flat as glass) the head(s), if needed (that's like the top of an ice cream cone for the pistons and were the spark plugs sit), and turn the crank shaft (it makes the pistons go up and down in just in time to work) hardly needs work but it can need to be replaced if broken; and finally the cam (cheaper to buy than mill most of the time) but the cam makes sure that everything with the crankshaft is getting the air it needs to run the engine.

If a rebuilder falls short in anyone of these areas then, your engine will not run long.

and how long it will run will depend on were the screw up was.

buy one from someone who will back up their work with a warranty. (not just 1200 miles) Good luck.