Help request for a 1975 DT 250 enduro conversion.

[Psychic Voltage]

So I have an old Yamaha DT250 enduro I like to convert into an electric commuter. I have never do an electric conversion before so input and guidance would be much appreciated. I need it to be fully able to live up to regulations of road vehicles, light and what not.

The idea was to keep the look but electrify it. Maybe gaining a little performance on the way.
I’m not sure if that’s possible on a budget, but I saw the stark futures warg and thought how stick should it be to have some of that in a small old classic.

I was thinking after researching a bit, to use a
QS138 90H – motor V3 gearing,
A controller something like a,
Fardriver ND96850
The battery I’m not sure about yet, but something like a,
72V 56Ah (4 kWh), I assume.
I also assume I would upgrade to disk breaks while I’m at it.

The thing is I’m located in Europe and I’m not even sure if these items are the best option since the whole tariffs thing have made it pretty expensive to import from the US.

If anyone has suggestions/ experiences with any thing like this, I be happy to take them. Alternatives on part sources and so on.

This bike is not mine, it was one from google. But same model and maybe a bit better quality.

 

[dominik h]

I have an original packed QS138-90H V3 and a also an ND961000 from November 2025.
I also have an unused ND96850 but it is 3 years old and you will eventually have Problems with the newer App Versions.

I checked it once with the App Version 1.5.5, but I installed first a ND72680 and later a used ND721800 which I had bought local for cheap and did not even think of installing the ND96850. You can always turn down if it should be to much, but if it is too weak you have to invest money and time.

I live in Europe.
Shipping is no problem.

My wife has canceled the Go-Kart project before I even started.

The 138-90H V3 will have more power and tourque as the old 2-Stroke engine, if your battery can handle the current

You can contact me via PM if you are interested.

 

[pwd]

Your motor/controller selection would be fine but I guess that you will want more than 4kwh of battery and a higher voltage than 72V (higher voltage will give you longer power band, more rpm and gearing flexibility) . Ultimately, it depends on the style of riding you'll be doing; how fast/far you need to go and budget.

 

[Psychic Voltage]

I have an original packed QS138-90H V3 and a also an ND961000 from November 2025.
I also have an unused ND96850 but it is 3 years old and you will eventually have Problems with the newer App Versions.

I checked it once with the App Version 1.5.5, but I installed first a ND72680 and later a used ND721800 which I had bought local for cheap and did not even think of installing the ND96850. You can always turn down if it should be to much, but if it is too weak you have to invest money and time.

I live in Europe.
Shipping is no problem.

My wife has canceled the Go-Kart project before I even started.

The 138-90H V3 will have more power and tourque as the old 2-Stroke engine, if your battery can handle the current

You can contact me via PM if you are interested.

Your motor/controller selection would be fine but I guess that you will want more than 4kwh of battery and a higher voltage than 72V (higher voltage will give you longer power band, more rpm and gearing flexibility) . Ultimately, it depends on the style of riding you'll be doing; how fast/far you need to go and budget.

Okey, I hade a suggestion that a higher rated controller would eliminate risk of strain on the system and give a higher safety margin. Is there any truth to that?

well I like it to be snappy ofc but ultimately it will be either city driving at relatively low seed limits( 30mph) or low highway seeds (55mph) either way a around trip for about 15 miles.

 

[dominik h]

If you don't run a system on the limit it should have less stress and will last longer.

The ND961000 is smaller im size, >easier to find a place and to install

But if you are aiming for a 72V System I also have a ND72680.
But I think the 72680 is too small for the QS180

 

[pwd]

Okey, I hade a suggestion that a higher rated controller would eliminate risk of strain on the system and give a higher safety margin. Is there any truth to that?

well I like it to be snappy ofc but ultimately it will be either city driving at relatively low seed limits( 30mph) or low highway seeds (55mph) either way a around trip for about 15 miles.

Yes there is truth to not running a controller (or anything else) at it's limits will make it last longer. Less heat = less wear but it depends how often you are pushing the limits.

15 miles @ 30-55 mph is modest in my opinion (you use imperial miles in Denmark???) but having more capacity will give you battery a longer life, better performance and give you greater freedom to ride. I'd recommend the largest battery pack you can fit and afford.

 

[j bjork]

You list a bunch of Chinese parts, and worry about importing from USA?
I think it makes more sense to buy them from China, or did you mean something else?

 

[SlowCo]

Great project but being in the EU might mean it will be very difficult and expensive to have it tested and approved for road use. Please check that before buying all the parts if you want it to be road legal and insurable.