Piston Kit Pro-Lite SeriesDesigned for all-purpose 2-stroke ridingDurability, longevity and increased horsepowerDedicated forging design for strength-to-weight optimizationExtra lightening operations for enhanced throttle responseEngineered, forged, and machined in the USAPiston is made in the USA'73-'80 Polaris EC44TX standard bore is 67.75 mm, stroke is 60.00 mm, bore oversize is +1.50. The rest of the Polaris models listed, the standard bore is 67.72 mm, stroke is 60.00 mm, bore oversize is +1.53 mm.