Bought my first bike and stupidly didn't check this (didn't check VIN either but luckily that matches). V5 arrived today and the engine number is different.

On the bike there is 2 lines of numbers on the engine and looks like this..

*E399E-*

then 2nd line looks like this (i put questions marks where the actual numbers are:

*??????*

On the V5 it looks like this. I put question marks for some of the numbers..

E399E0??????

So the first few characters match but basically not the 2nd line of the engine. The owner didn't mention anything, I know I should have checked and asked but is this heard of to have a partial mis match before I go back and ask the previous owner?

Should I inform the DVLA of the change if the previous owner does/doesnt know about it? Is there anyway I can investigate further? Its only had 2 MOTs due to being 2009 and the mileage seems to tally up.

Not sure if I should be concerned or put it down to experience. I guess I am more concerned of notifying someone in case the engine was stolen or struggling to sell it due to people being more vigilant than I was.

I wouldn't worry about it too much, if i were you!

On my V5 it has 8 digits for the VIN number. BUT for engine number it simply says 'not known' - and this is after the DVLA sent it back in my name. ALSO the engine number is on the engine of the bike, not sure why it's not on the V5.

Also it concerns me that it could have a different engine in and dont know how that might have been used/abused

Also it concerns me that it could have a different engine in and dont know how that might have been used/abused

but how would you know this if the numbers matched?

At least If they matched then i know it was the engine it was manufactured with and could trust the mileage on the mots

You can change the engine number on the V5 and send it back to the DVLA for a new V5. Many reasons for engine changes so unless you paid top money for it I wouldn't worry.