Engine Trouble identification

[GEEZ]

have motor and at base of cylinder on R/S is stamped '2018' plus cylinder and head are 1piece. l would like know what size it is ? so i may top end up grade. thanks for your time & knowledge , G

 

[Chainlube]

have motor and at base of cylinder on R/S is stamped '2018' plus cylinder and head are 1piece. l would like know what size it is ? so i may top end up grade. thanks for your time & knowledge , G

Most likely 80/66cc, best way to make sure is take the cylinder off and measure the piston. 47mm = 66cc.