There should be no problem selling a french bike in Norway. There is, however, some paperwork to be done. The EU is also the EEA, but the EEA is not the EU, so any bike approved for use in the EU is also approved in the EEA. Just bring your motorcycles documentation or a CoC document.
Some of this can be done by the buyer. But it is strictly forbidden for a Norwegian resident to ride a vehicle on foreign licence plates, so if you leave the paperwork up to the buyer he will not be able to test ride it before he has got the norwegian licence plates. If he's caught riding a foreign bike in Norway he will likely be fined and have to pay a penalty tax in addition to the standard import tax on bikes.
There is a pretty high import tax on motorcycles in Norway, but you don't have to pay that as long as you intend to take it out of the country again. The selling is what triggers the taxes.
On top of your price, the buyer will have to pay 25% VAT, registration tax, horsepower tax (for lack of a better word). This all depends on what type of motorcycle you have.
To calculate what the total tax will be, use this:
Calculator: importation of motor vehicles - Tollvesenet
More general information here:
Vehicle importation - Tollvesenet
Now, selling your french motorcycle in Norway might be expensive for you. Have a look here and check what the going price for your motorcycle is:
Motorsykkel til salgs - FINN MC
If your price, pluss the taxes is more than what the going price is, you might be better off selling it at home.
So, here's what I recommend you do:
Check if you can actually get a good price for your motorcycle. Depending on what type of motorcycle, you might be lucky.. If you are 100% sure that you can sell the bike for a good price go ahead and do the whole import thing. This procedure starts off at a customs office by paying VAT on your bike. The rest of this procedure can be read here:
Vehicle importation - Tollvesenet
Remember, on motorcycles the tax is dependent on the age of the bike, engine volume and horsepower. As an example: A bike with 75hp and a 650cc engine would get an import tax of nearly 48 000 NOK if it was brand new. If it is from, say, 01.01.2000 that is lowered to 15 800 NOK and if it is older than 1995 tax is 9 600.
Older than 1980, and it becomes a "veteran" vehicle and the import tax goes down to 3500 NOK.
25% VAT comes on top of the sales price but before the import tax.
Hope this makes sense..