Over the years I built a lots of dirt bike and quads crankshafts. I used aftermarket rods supplied by different sources,with no problems. Over the last 30 years I had information of rods lengths ,upper and lower bearings including thrust , pins and clearance information. Buttttt I have lost those old catalogs with an endless supply of accurate information. Here is the question is why not use these rods from mx ect. In our kart engines??? We all had those old 80 up to 250 2 strokes we beat on growing up . We didn't. Have the best oils or information about them but they were tuff as nails.