Assuming that you have the bike registered already with the correct frame number all you have to do is notify DVLA of a change of engine with the new engine number. They will do various checks to establish where the new engine came from and obviously if it is from a stolen bike you can expect a knock on the door from Mr Plod.
Suggest that if you are going to acquire a different engine you get a proper receipt for it and hold on to it.
Assuming everything is above board DVLA will return your registration document showing the new engine number.
BE WARNED - your insurance company will also be aware that the bike now has a different engine and may well quote you a ridiculous renewal quote on the grounds that it is now a 'modified vehicle'. It makes no difference to them that it is an identical engine, they merely see it as modified from original specification and load your premium accordingly.
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Assuming that you have the bike registered already with the correct frame number all you have to do is notify DVLA of a change of engine with the new engine number. They will do various checks to establish where the new engine came from and obviously if it is from a stolen bike you can expect a knock on the door from Mr Plod.
Suggest that if you are going to acquire a different engine you get a proper receipt for it and hold on to it.
Assuming everything is above board DVLA will return your registration document showing the new engine number.
BE WARNED - your insurance company will also be aware that the bike now has a different engine and may well quote you a ridiculous renewal quote on the grounds that it is now a 'modified vehicle'. It makes no difference to them that it is an identical engine, they merely see it as modified from original specification and load your premium accordingly.