Piston ring installation jig and piston ring installation method using the jig

A piston ring installation jig to be used when installing a first piston ring, having a ring gap, in a first ring groove formed in an outer peripheral surface of a piston, the piston ring installation jig comprising

• a main body having a first main body portion having a semi-cylindrical shape that is configured for surrounding the outer peripheral surface of the piston,
• the first main body portion comprising a first arc shaped groove formed in an inner peripheral surface of the first main body portion in a region located as to correspond to a location of the first ring groove of the piston such that a portion of the first piston ring in a circumferential direction is insertable into the first arc shaped groove, and
• the first arc shaped groove defines a circle which has a circle center biased more to an outer peripheral side of the first main body portion than a circle center of the inner peripheral surface of the first main body portion, and wherein
• the piston has a second ring groove separated from the first ring groove in an axial direction,
• the main body comprises a second main body portion disposed opposing the first main body portion as to form a cylindrical shape,
• the first main body portion has the first arc shaped groove in a region corresponding to a location of the first ring groove of the piston, and has a first non-groove-formed portion located in a region corresponding to a location of the second ring groove of the piston, the first non-groove-formed portion being defined by the inner peripheral surface of the first main body portion, and
• the second main body portion has a second arc shaped groove located in a region corresponding to a location of the second ring groove of the piston, and has a second non-groove-formed portion located in a region corresponding to a location of the first ring groove of the piston, the second non-groove-formed portion being defined by an inner peripheral surface of the second main body portion.