The bore CANNOT reach 180cc I'm afraid. 134cc with the powervalve intact although shaved. Any more than this and you will need to remove the powervalve since there is no room left to machine off the PV.

The only way you could get close to 180cc is by have the Athena kit. But even then the Athena kit is SO underpowered that it wouldn't warrant doing.

You get better results boring and tuning the standard 125 barrel.