tufty

Hi , i have just bought my son his first field bike a dt 125, however the engine seems to have seized, the number on the engine casing states ita a 3bn y-1 with y-2 on the barrel.would anyone know which piston and rings would fit this or is it better to try and find a secondhand engine and if so do other engines fit straight in regardless of age or make? as you can imagine the poor ol' boy is gutted only had it a week. also looking for a mikuni rr-oo carburettor to suit as well or again will most ages of carbs fit, thanks in anticipation the bike i believe should be a 2001 but as a stolen recovered field bike i'm not sure.