Products Snowmobile- YamahaPiston Kit Back Piston Kit 09-816 Item number: 09-816 Bore Size: 73mm Stroke: 64 Fit on model: 1983-91 Yamaha VMX 540 You May Also Be Interested In Piston Kit 09-807-02 Piston Kit 09-813-01 Piston Kit 09-780-03 O-Ring 420-931-410 / 931410