Wiseco Tracker Piston Series has a forged piston crown with generous valve pockets for big valves and cams. Precision fit rings. Force fed pin oiling. Selected for each application for ultimate sealing. Enhanced lubrication of the piston pin. Pressure seal groove.. ArmorGlide skirt coating. Reduces ring lifting and power loss. Reduced friction, quieter operation, improved scuff resistance. Evolution Big Twin 1340 Evolution Big Twin 1340, Compression: 10:1, Displacement: 1340cc, Bore: 3.498"/Std, Stroke: 4.250", Domed, +12.9cc