Prior to installing used or new rings, clean the cylinder bore, insert a ring in it and ensure you measure the ring gap when it is set at least 12mm (0.50 inch) from the lowermost part of the cylinder bore. Remove the
Piston, square the ring in the box so it's centered, then lower it into place and check each ring with a feeler gauge, changing them if they are not as specified. Clean the walls of the piston ring grooves and check them for damage; then, hold the feeler between the piston ring and the ring groove and replace any ring that doesn't fit properly. Spin the ring on the piston rod to check it rotates freely around the groove. Because the No. 1 and No. 2 piston rings are different, make sure the No. 2 ring has the minor side facing up towards the top of the piston (the side with the manufacturer's I.D. or Dot on it). First is the oil ring expander, then the upper oil ring side rail, the lower oil ring side rail, followed by the No. 2 intermediate piston ring and finally the No. 1 upper piston ring. After installing the oil ring expander, slide one side rail into place between the piston ring and the expander, grip it, push it down and repeat the process for the lower side rail. It is important to use a piston ring installer when you put in both the No. 2 intermediate and No. 1 upper piston rings. Arrange the piston ring end gaps so that the expander ring gap is about 45° away from the sides, not at the piston pin center or in the thrust direction.