Piston and method of making a piston

1. A method of making a piston comprising the steps of:

preparing a single piece upper crown member of cast steel having a top surface, a combustion bowl recessed in said top surface and an undercrown opposite the combustion bowl, wherein the combustion bowl and the undercrown has a final finish form that is produced by casting;

preparing a lower crown member as a discrete component separate from the upper crown member;

joining the upper and lower crown members together;

machining at least a portion of said joined upper and lower crown members other than said undercrown and said combustion bowl; and

wherein the combustion bowl includes at least one irregularity spaced radially from a central axis and extending less than circumferentially around the central axis.

2. The method of claim 1 , wherein the top surface has a final finish form that is produced by casting.

3. The method of claim 1 , wherein the joining step includes joining annular ribs of the upper and lower crown members together with the undercrown being formed over an entirety of a region extending radially inwardly of the annular ribs.

4. The method of claim 3 , wherein the entirety of the undercrown has a final finish form that is produced by casting.

5. The method of claim 3 , further including forming an oil gallery radially outwardly from said annular ribs upon joining the upper and lower crown members together and providing an upper surface of the oil gallery having a final finish form that is produced by casting.