The face of the upper and intermediate piston rings should be placed on the piston with the identification mark facing up. You should put in the oil ring expander, next the upper oil ring side rail and then the lower oil ring side rail. To install the side rail, place one end where the piston ring groove meets the oil ring expander, hold it tightly and lower it so it slips into place, without using the piston ring expander. Markings on the compression rings are Y1 for the upper ring and Y2 for the lower ring; you will see these markings when you look up from the cylinder. Then, fit in No. 2 piston ring and install No. 1 piston ring next. Put each piston ring gap slightly far from the other rings and set the oil ring expander gap away from the closest side rail by at least 45°. Also, avoid positioning the gaps in the area of the piston pin or thrust direction, since having slight gaps will better control the oil.