So there are many ways to lighten rods and pistons and cranks. But the trick is in the balance.
1. Static Balancing. Make all things the same, the same weight. So you make all the pistons within 0.1g and all the rods within 0.1g of each other. You also need to measure the front to back on the rods and check them for twist. There are only certain places you an lighten the rods (even less on AE111 rods). What about the crank? hwo do you statically balance it?
2. Dynamic Balancing. Bolt it all together, clearance it, then hook it up to a dynamic balancing machine that will tell you the rotational out of balance - kind of like a wheel balancer - except they go to the nearest 5 grams, whereas you want to go to the nearest 0.1g.
So in the real world, your engine builder had to close and hone the rods and linish the crank, which meant he had to put thicker bearings in, and he tunnel bored the block and the mains had to be linished and the crank was a bit of out of balance to start with. Boom, you are now waaay out of balance as your rods and pistons (and flywheel/clutch and main pulley) are all bolted together to be balanced. Yes inidvidual balancing helps, but it's better to balance the whole kit and caboodle.
So unless you have a dynamic balancing machine at home, you won't be able to get anywhere near a 0.1g, let alone a 1 or 10g dynamic balance on the rods/pistons/crank/flywheel/clutch/pulley. Leave it up to a professional engine builder, but be prepard to fork out lots of cash for him to do it.
