A bit of a weird thread title, but here's the story: I've got three 2nd-gen 750 engines and have to choose two to keep. I don't want to pull them apart to inspect and wreck the gaskets, and they're not all in bikes so i can't ride/dyno them all. One is a spare that's not in a bike. It came with the first bike I bought. The clutch-side cover is missing but it looks clean inside. Of the other two, one is reported to have about 90,000km on it, and the other was apparently 'rebuilt' (whatever they mean by that) about 5,000km ago. The ones in bikes both start and run fine, though I haven't ridden them cos they're not road-worthy yet. I'm going to keep one bike and spare engine, and sell the other bike when it's ready. I'm thinking that on each engine I should inspect the cams/rockers for wear, check compression (maybe leakdown test?) and could even pull the engines and visually inspect inside via the oil pans. On the spare I have, I can see the bottoms of the bores when the oil pan is off, and can see cross-hatching on the lower bores. That's a good start, but probably doesn't really tell me too much. Any thoughts, advice? Cheers.