(UK) Legally converting motorcycle to moped classification?

So I'm wanting to take an existing vehicle and turn it electric - skip the MVSA, no Q plate, probably be cheaper, so on so forth. Originally I looked for 50cc mopeds but I don't like the look of scooters and actual mopeds are rarer and relatively expensive.
125cc motorbikes though? Can't stop tripping over them.

I've read up on changing the engine on the V5, but its not clear if changing a 125cc engine out for a 4kw, max 45kph would legally change the bike to a moped. That bits important because my license only stretches as far as 50CC. The DVLA contact form just sent me around in a loop and didn't want to spend £10 idling on the telephone just yet.
Has anyone successfully done this previously or should I just bite the bullet and get an A1 license?

Just get your A1 license and buy a motorcycle and ride it.
Not worth the hassle trying to do what your doing.

If you do go ahead, just buy a motorcycle and ride it, no need to convert.
Your just making more work for yourself.

Have you read the other half dozen threads on your exact same issue?

Think converting 50s and 125 mopeds and scooters is a great idea its next logical chassis for more speed after a ebike conversions good to 30mph,
but escooter be good for 60mph having more suitable suspension, tyres, brakes and lighting and able take weight larger battery
UK gov has targets for vehicle emissions so imagine would be more positive about such projects at the moment,
Saw nice bike on vintage voltage programme recently,
after quick look not found a lot of conclusive info except this cool bike on here
https://endless-sphere.com/forums/viewtopic.php?f=12&t=80785&hilit=Mt50
so if you do make that painfully long phone call as with all things gov related, I'd be very interested know how you get on :thumb: after all would be very environmentaly friendly recycle all those great chassis that are available with blown engines (i have a prime 125 in shed) and making them run quietly and cleanly can't see any negatives

I’ve been there with the same topic - lots of folks have previously tried to change engine class of a 125 to 50cc to use it on a moped licence and DVLA are wise to this. I even looked into doing something similar with a wrecked Zero FX and downgrading motor but DVLA wanted a formal engineers report and expensive power testing on a dyno to prove power output.

Tbh if you want to stick to using your moped/drivers licence buy a 50cc and convert with a 4kw motor (remember that’s continuous so will well exceed 30mph if you want!) … that’s what I did initially using a Yamasaki donor bike . https://endless-sphere.com/forums/viewtopic.php?f=12&t=105463

Or take your CBT/A1 test and convert a 125.

The cost of the donor bike will be far less than the cost of motor, controller. Batteries and sundry other items