have used the search option and want to clarify. I have a 2006 YZ450F that is mechanically stock with the exception of the Zip Ty carb mod and JD jet kit to get rid of the lean condition. Fact is the 450 is a little to much bike for me. I rode a buddies 250f and it was not enough. I am not a small guy at 6ft and 225 lbs so I want to keep the beefier suspension of the 450, but I would like to soften the motor up a little. I had a 99 400 and the motor fit me perfect, but I didn't like the extra weight and the suspension was not near as good as the 06. I have a heavier GYTR flywheel that I will be installing this week. My question is: If the flywheel does not do what I want, exactly which WR will I need to use and what other affects will it have, i.e. starting? What set up will I need to use for timing? I would appreciate any inputs. Thank You.