The most expensive part in this assembly is the Crank Shaft Comp..
Parts such as the Crankshaft - Chart: Ring Set,piston (, Ring Set,piston (, Key,woodruff 25x1, B/brg Rad N/com are included in the Trx250x Fourtrax 250x 1991 (m) Usa Crankshaft - Chart parts fiche.
In this schematic the "Roller A,4x16.8" is used most often.