I am thinking of buying an old air-cooled mono that has been restored, and whilst doing this a replacementengine was fitted. This means that the frame number matches the one on the log book but the engine number doesn't. The bike is registered to the correct address and I know it's not stolen. It is not currentl taxed or mot'd but I would want to get it back on the road for road trials. What imPlications would it have if any? Would anyone other than me ever even know?

Well, imagine how many cars there are with reconditioned engines fitted where the engine number doesn't match the logbook.

DVLA staff are so vague on their own procedures that you would get 3 different answers from 3 different staff if you asked what you should do. As usual, red tape makes it vitually impossible for us to simply update a vehicle record honestly. I'd leave things as they are, the important one is the chassis number and that matches the V5 and registration.

If you do decide to update the V5, you need to provide DVLA with a receipt for the replacement engine from a trader, if bought from one, as proof that it is legitimately bought and not stolen. If you do not have this, or the engine was bought from a private seller, then you would need a letter from the manufacturer (no idea of the poinbt of this...) or an inspection by DVLA to ensure the engine isn't on their stolen list.

There are no implications in terms of getting it back on the road. The MOT certificate only requires the chassis number which they usually take from the logbook if you take it with you, there is no requirement for the engine number at MOT. Insurance only want the registration number and although the engine is a replacement it is of the same type so the bike isn't modified. Road licence application has no requirement for engine number.

Well, imagine how many cars there are with reconditioned engines fitted where the engine number doesn't match the logbook.

DVLA staff are so vague on their own procedures that you would get 3 different answers from 3 different staff if you asked what you should do. As usual, red tape makes it vitually impossible for us to simply update a vehicle record honestly. I'd leave things as they are, the important one is the chassis number and that matches the V5 and registration.

If you do decide to update the V5, you need to provide DVLA with a receipt for the replacement engine from a trader, if bought from one, as proof that it is legitimately bought and not stolen. If you do not have this, or the engine was bought from a private seller, then you would need a letter from the manufacturer (no idea of the poinbt of this...) or an inspection by DVLA to ensure the engine isn't on their stolen list.

There are no implications in terms of getting it back on the road. The MOT certificate only requires the chassis number which they usually take from the logbook if you take it with you, there is no requirement for the engine number at MOT. Insurance only want the registration number and although the engine is a replacement it is of the same type so the bike isn't modified. Road licence application has no requirement for engine number.

Excellent, thanks for the info. Pretty much what I was hoping to hear. Much appreciated.