Which engine should I go with??

[Dhawk12]

This may seem like a dumb question, but I will ask it anyways. I have 2 pre-kat 750's, my daily rider which is an 89 with 70,000 km (44,000 miles) on it, and a 97 that I just picked up for cheap with 40,000 km (25,000 miles) on it. My plan is to make one really good bike out of the two, and sell the other one, but I am torn as to which engine to go with. Yes, I know it seems like a no brainer as one has almost half the km, but I am pretty sure that my 89 has been well looked after for its 70,000km and the other one is an unknown entity. Any suggestions? I plan on taking the 97 engine apart to do valves etc., is there anything I should look for to make an informed decision on which engine is better at this point? When I got the 97 it had an aftermarket V&H SS exhaust on it, but the carbs were completely stock, so it is possible it has been running quite lean for an unknown amount of time.

[rperry03]

Miles don't mean much at all. Which engine runs better, sounds better?
Do a compression and leak down test along with checking the oil pressure.
When you get inside the engine take a look at the crosshatch pattern.

[shpielers]

+1
I'd do the compression and leak down. If they both come out comparable, go with the newer/fewer miles one.

[92xjunker]

If your selling the leftovers as a bike then use the low mileage engine.

[Dhawk12]

Good call on the compression and leakdown tests. I will do those when I get some spare time.