just found this quote on another site
Please note the Chinese clone Honda CG125 overbore and big bore kits will not fit on genuine Honda CG125 engines.
I have emailed a few Honda CG owners who were disappointed when they bought their kits and did not fit.
The reason the Chinese CG150cc kit does not fit is the liner is OD 67.5mm (to big) and the Honda CG crank cases are only OD 64mm (to small).
So to be made to fit would take full engine strip and major machine work to crank case, and the danger of breaking into one of the oil ways.
Remember this work will not be cheap and not all Honda Cg125 crank case will be able to be machined bigger.
Honda changed the design of crank case over the years.
whether there are differences between the xr and cg that will make this possible i do not know..
Etienne if i find more info i will let you know k,if you have any luck let me know mate.......boyakasha