Well...any exporting company should be aware of what they can and can not send across borders....if you talk to a private seller then you will have to ask questions.
The bike has to have a FMVSS or CMVSS label affixed to it these mean Federal Motor Vehicle Safety Standards (U.S.) & Canadian Motor Vehicle Safety Standards) dirt bikes need off-road labels attached too...
Here go to this and make sure search by manufacturers name is checked, (it should be, if not then do so) and type in the Original equipment manufacturers name (ex. KAWASAKI) if it shows then the vehicle is admissable, but contact RIV by phone to double check.
http://www.tc.gc.ca/roadsafety/impor...2&im=&reload=2
Most dirt bikes, pocket bikes, mini bikes,etc... are admissable as restricted use motorcycles.....