Thanks for the nice comments folks. Docstory - geez I sure hope not.
Went down to the engine shop and weighed a bunch of 149 tooth flywheels. They pretty much all weighed the same.
Average normal 149 tooth flywheel = 106.920oz/6.682pds
Mine after cutting off the pulley = 86.915oz/5.432pds
Skydynamics flywheel = 47oz/2.937pds as reported on their website (http://www.skydynamics.com/frame.htm)
So cutting the pulley saves just 1p 4oz. Really not all that much. But going from a full normal flywheel to the flyweight one from Sky Dynamics will save 3.75 pounds. Thats pretty significant, especially since that weight is way out front.
This is my flywheel before trimming the pulley off
This is my flywheel after trimming the pulley off. My good friend Tom popped it on his lathe and had it done in a flash. Some like DW and Doug K have also drilled out theirs
This is a picture of the Sky Dynamics magnesium Featherweight flywheel.
Hope this helps. You will have to decide what works for you.