Piston +.010 / Briggs & Stratton 499957Pack Size:1Briggs & Stratton 391287, Briggs & Stratton 394956, Briggs & Stratton 394662, Briggs & Stratton 498585, Briggs & Stratton 499286, Briggs & Stratton 499957ESF 163-151, Foley/Belsaw 5978375, Foley/PLP 163-151, Laser L5647, Laser 94236, NHC 266-8591, Oregon 36-313, Oregon 36-216, Prime Line 7-03515, Prime Line 7-03848, Prime Line 7-03509, Rotary 6726, Sunbelt SB-6726, Sunbelt B1SB6726Briggs & Stratton 220000-222000, 252000-257000, 280000-286000 and 400000-422000Ethanol: Not compatible with greater than 10% ethanol fuel, Cylinder Bore Size: 3.4465"-3.4475"