This flywheel talk reminded me of the Stealthy flywheel weight I put on a YZ250 two stroke. Here is their explanation:
"About Steahly Offroad
When we started making flywheel weights in 1987 very few riders understood the benefits of adding flywheel weights. Since then the popularity of adding flywheel weights has increased dramatically. More and more riders discover that they can go faster for longer with the smooth power delivery, better traction, and reduced stalling that Steahly Flywheel Weights provide. Adding a flywheel weight will increase the rotating mass, or inertia, of the motor. The result is an engine that is a little slower to rev, has more controllable power delivery and less hard hitting power, a more usable low to mid-range, and is less likely to stall at slow speeds or with the rear brake. What you will feel is better traction when it is slippery or hard pack, a torquier and broader powerband, and the top end power on many bikes will be improved with less tendency to lose RPM’s when climbing or hitting obstacles.
The easier to control power will help you conserve your strength and energy, plus many bikes start easier with the added weight."