It is impossible to dynamically balance a single cylinder engine due to the difference between linear motion of the piston, and rotary motion of the crankshaft balance weight. Double web cranks balance better than half web cranks. Then there is the connecting rod with it's rotary part and linear part. Target is to balance about half the linear moving masses, which should result in equal vertical and perpendicular imbalance. From there, you must experiment to get the best rusults, using more or less balance weight depending on the engine mass distribution.