The "extra weight" I was referring to was the slug. You still remove material to install the slugs yet they can be positioned incrementally +/- of the zero balance point.
The "inertness" of the added weight in a single cylinder engine when placed in different positions on the counter weight will aid or detract in the torque being built by the firing of the cylinder.
If there is no effect why are the slugs placed where they are in the counter balance? They are opposite of the knife edge and right of pin center. Why not just manufacture the crank correctly in the first place?
