I have a stealey flywheel weight on my KDX 220. I like the way I can lug the bike on really hard sections of tight trail. Just open the trottle above idle and the rear wheel keeps churning. In boulder strewn trails, or coming out of rocky river up a steep bank, there is little chance stalling the bike. I'm sure if you were on a M/X track or ride in the desert your bike would not rev as fast.But in the type of riding I do ( hare scrambles, enduro, single track trail) I can't tell the difference. If you have a worn out engine a flywheel weight can cause problems, my bike is brand new. I like it! $90.00