Nikasil?
#21
#23
Are you sure it's opened before? Are there any marks of that? The density of the cast can vary and allso the thickness of the counterweights because of the tolerances. There can be actually many grams difference between the counterweights when it comes from factory after balancing. I would get it checked at machine shop that balances crank before throwing it away. I got mine rebalanced when i started my rebuild and the balancing was way off. Never opened before and the crank was straight and crank pin were ok so i would guess it has leaved factory the way it was.