Mr lilley wrote
The rod bearing wear is accelerated by the un-counterweighted crank flexing
in the center and edge loading the = rod bearings as the rod journal is thrown
off perpendicular to the = rod.

Counterweighting the crank keeps all the crank angles true, bearings last
longer (Often doubles bearing life), power increases, flywheel = can be
lightened to increase acceleration and only adds about $150 to a = WBX rebuild.
This is according to Gene Berg's tech articles.
My counterweighted WBX at 5800 rpm is smooth.
Robert