declaring my aerox with a 125 typhoon engine. How do i do it?

i know it needs to be MOT'D again but do i send the log book off now and then MOT it but then do i risk not getting the log book back for ages and not been able to MOT it...

 

I changed it myself and bought the engine privately with no reciept of sale though

 

When I fitted my 250cc twin to my typhoon, I just sent the log book off to DVLA with a change of cc only, there not interested in the cc. It's when it's time to change down on cc's like a 125/180 to 50cc that they want to know all the in's n out's s they are getting less revenue in road tax!

 

So if I just get it motd and send the log book off? And all is well