Athena (S4F05300002A) 52.95mm Forged Piston Kit Fits: Yamaha YZ 85 2002-2013 Specifications: Big Bore-52.95mm (A) Forged Piston Kit Athena developed their forged pistons specifically for use in the off-road/ATV market and manufactured them using a revolutionary computerized technology originating from GP and F1 racing Athena forged pistons offer the best solution in terms of performance and reliability thanks to redesigned squish areas, modified compression characteristics and advanced surface treatments Piston is sold complete with rings, wrist pins and circlips