yamaha TTR250 piston rings

[DVS ME]

Hi does anyone know where to get custom rings from? The trouble i have is the bike has been bored 3mm and im not sure what piston and rings they have used. I have been to a few bike and engine shops but no luck yet.
any help would be great thanks

[tommorth]

are there any markings on the piston to indicate who it was made by?

[barty5]

what size piston has it got at the mo???