Two words for you, Flywheel weight. 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. This is stright from this site
http://www.steahlyoffroad.com/about_steahly.shtml
Good luck.