On this parts fiche the Bolt,conn.rod is the most specified component.
Parts such as the Piston - Connecting Rod: Bearing D,con-rod, Bearing D,conrod, Ring Set, Piston, Bearing E,conrod are included in the Cb250n 1978 Belgium Piston - Connecting Rod parts fiche.
Of all the components used in this assembly the Rod,connecting is the most expensive.