Hi Gorka,

As mentioned in dannys Tianjin-thread, it is not possible to legally plate a bike within the city. But since you are in Dagang, it should be possible.
Regarding dealers, inside Tianjin I only know of a grandma who accidently sells some random 125CC bikes among the Electric Bike dealers in Tiantai Lu and the Harley Dealer in Meijiang.
In Proximity you have the motorbike dealers in Tanggu, but I would advise to stay clear. You can't be sure where the bikes are coming from, who owned it before (or maybe still owns it, technically) and who exchanged which part with what. Not a good base for a 'legal' plated bike.

There is also a Suzuki dealer (I think in that area?) who can service motorcycles, maybe they can sell them, too. Phone number is 022-83988380.

And we will always have... Beijing. Qili Motors (near Jiugong) in Beijing has CFM and a lot of other bikes, BeijingRiders works too, if you don't speak chinese (or just unable to locate Qili), but I don't think they have CFM (but Benelli).

dannythewahl and me both have our bikes licensed in Beijing, also since we live inside the bike-ban area in Tianjin.