I work in a machine shop thet manufactures all types of severe service industrial pumps. When we balance the impellers, we have precision scales to keep track of metal removal (or sometimes adding). If you guys need a specific oz. removed I could possibly help. Send me your flywheel, and I can machine it down, and document the old/new weights to whatever you want. I know my Stealhy weight is 14 oz. And it made an awesome enhancement of torque down low, I felt little difference in "revs". If anything I do notice a longer over-rev WOT. I don't need to comment to you KX500 guru guys, when shaving your flywheel, go INCRAMENTALLY small removal rates. You can always shave a bit more, rather than have taken off "too much".
Rich