If the Crankshaft is Not Installed

Remove the connecting rod caps, then install the ring compressor, and check that the bearing is securely in place.
Apply new engine oil to the piston, inside of the ring compressor, and the cylinder bore, then attach the ring compressor to the piston/connecting rod assembly.
Position the piston/connecting rod assembly with the arrow (A) facing the cam chain side of the engine block.

Fig 1: Identifying Arrow On Piston
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Position the piston/connecting rod assembly in the cylinder, and tap it in using the wooden handle of a hammer (A).
Maintain downward force on the ring compressor (B) to prevent the rings from expanding before entering the cylinder bore.

Fig 2: Positioning Piston/Connecting Rod Assembly Cylinder Using Hammer
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Position all pistons at top dead center (TDC).