Yz125 registration

Hi, so im 18 and recently brought a yz125 (my dream bike) 1999 to turn into a supermoto that i can fully rebuild. The only issue being the registration. 

i have already applied once and been denied, on the dvla letter it said that they cannot except copys of a conformity letter(even though i sent the original?!) and that i needed to get a NOVA certificate even though the bike isnt imported…

i was wondering if anyone has registered a bike for the first time and could please maybe produce a list or further explain what i need to do? 
 

my bike also has a different VIN and engine number as it has had a different yz125s engine put into it, unsure if this matters but any help is appreciated. Its a right bloody pain 😂

Fyi Im based in the UK and we may have different registration processes

Edited March 29, 20223 yr by TheJam