O.S. MAX 15CV-RX Engine (L-OS11640) The ultimate combination of performance & convenience in a side exhaust 15-size engine. If the class you want to race in allows 15s & you want the best, then take a long look at the Max 15CV-RX. Its not cheap, but the best never is! Supplied with standard shaft, drive washer & rotary 10E-R carburettor. Specification: Weight: 253g Displacement: 2.49cc 0.152cu. In. Bore: 15.2mm 0.598in Stroke: 13.7mm 0.539in Power Output: 1.2/31000 (BHP/RPM) Practical RPM: 4000-36000