What motor and controller, dirtbike 60KW plus

D

Dailyride

100 µW
Joined
Apr 14, 2025
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Netherlands
After thinking it over for a few weeks, I’ve decided to build an electric dirt bike. Right now, I’m researching controllers, as I want the performance to match that of a Stark VARG. I’ve seen a few different motors and controllers, but I’m having trouble choosing — especially with understanding the specifications of the Fardriver controllers. The kW ratings don’t always seem to match what’s listed, or maybe I’m misunderstanding something?


I’m aiming for over 65kW of peak performance, so if anyone has suggestions, I’d love to hear them. I’ve been considering the Votol 550 controller or one from Fardriver. For motors, I’ve been looking at the TM50 or 180QS. If anyone has experience or recommendations for this type of build, I’d really appreciate the input!
 
There's that new controller from Kelly:
kellycontroller.com

KHS - High Voltage Opto-Isolated Sinusoidal Motor Controllers (320V-360V) (200A-400A) - Kelly Controls

High voltage controller using IGBTs,minimum overshoot, nice waveform. Superior heat dissipation, IP66 rated waterproof controller by default. Built-in Supervising micro.
kellycontroller.com kellycontroller.com

360V * 400A = 144kW.

As a commuter, I've never gone over 3kW myself. That's plenty to go 30mph, after which the cops would just stop me anyway, so no point.

Even donated my motorcycle to charity after breaking my leg last accident and my daughter missing me too much while I was in the hospital.
 
ND961800 (76kw peak) or ND961800 plus (105kw) or ND961800 plus Racing Version ( 125kW)
or the108V Version of the controllers above , if they are available now.

I think Fardriver ratings are for continous power over a long period.
 
The EVE INR21700-40PL cell has a 70A discharge rating.
RC lipos could also be used (with extreme caution).
There are also some hybrid car cells that have a very high discharge rating.
 
I mean we already know what battery can supply the power a Varg needs - it's the one that it's inside the Varg. And we also know it's built with Molicel 21700 cells, running a high voltage, high rpm motor with a dual reduction drive.

It's very likely that your bike would also need to fit those constraints. The new Kelly controllers certainly look like an affordable, high voltage option that was missing on the market for a while - the "real deal" of non-Chinese, regular industry use controllers run eye-watering prices. Unfortunately, it's likely you'll have similar issues with the motor and the reduction drive. Unless you are very lucky or have a very capable machine shop, it's going to be hard to find affordable motors that will spin fast enough to generate the power you seek while keeping the weight and size low - and you can't exactly go bigger, because your battery also needs to fit in the frame. Did I mention you'll need an extremely lightweight yet extremely strong (as we're talking 350-ish 21700 cells) battery case?

If your only goal is to beat the Varg no matter the cost, sure. If it is to build a comparable bike for cheaper, you'll need to input considerable resources and capabilities to make it happen.
 
bananu7 said:
I mean we already know what battery can supply the power a Varg needs - it's the one that it's inside the Varg. And we also know it's built with Molicel 21700 cells, running a high voltage, high rpm motor with a dual reduction drive.

It's very likely that your bike would also need to fit those constraints. The new Kelly controllers certainly look like an affordable, high voltage option that was missing on the market for a while - the "real deal" of non-Chinese, regular industry use controllers run eye-watering prices. Unfortunately, it's likely you'll have similar issues with the motor and the reduction drive. Unless you are very lucky or have a very capable machine shop, it's going to be hard to find affordable motors that will spin fast enough to generate the power you seek while keeping the weight and size low - and you can't exactly go bigger, because your battery also needs to fit in the frame. Did I mention you'll need an extremely lightweight yet extremely strong (as we're talking 350-ish 21700 cells) battery case?

If your only goal is to beat the Varg no matter the cost, sure. If it is to build a comparable bike for cheaper, you'll need to input considerable resources and capabilities to make it happen.
Click to expand...
its already done, ive seen it on the forum here.
What i am looking at now is the ND961800 and the qs 180,
Mabye the kelly controller is also an option but what is the point?
Ive seen a lot of fast things with those far drivers.
 
Theres not particularly relevant but there is a fairly interesting offering from greentec, they have a couple semikron skai2 GD06-2050WCIs which are rated at 450v and 300 amp, roughly 135kws, probably a bit overkill for this application but they are really cheap for what they are...Guess the hassle/cost would be in figuring out the programing interface and a cooling solution...

As for actual controller and motor recommendations, qs180, maybe some of the motenergies, the zero z75-7r and -10 as well...
Would probably stay away from the torp/sotion offerings since the claimed ~10-13kg seems oddly low for something that has a claimed output of 50 odd kws. Controllers would probably boil down to the already mentioned fardriver and kelly, as well as possibly sevcons, though that really depends on your motor...

There sadly arent really many small, high voltage motors that can take a lot of power and would fit into something like a dirtbike/motorcycle...Would love to see some ~300-400v offering from the likes of qs but I suppose there isnt much market for it...

The main constraining factor in a build like this will be the battery, I would probably be better to pick out a frame and design a battery around it, then just simply going for the largest controller and motor that can be powered by said battery. Would be a shame to have a motor and controller capable of much more than is able to be supplied by the battery...

And also dont forget whatever you end up going with its going to be very heavy 😃
 
Last edited:
thebes said:
Theres not particularly relevant but there is a fairly interesting offering from greentec, they have a couple semikron skai2 GD06-2050WCIs which are rated at 450v and 300 amp, roughly 135kws, probably a bit overkill for this application but they are really cheap for what they are...Guess the hassle/cost would be in figuring out the programing interface and a cooling solution...

As for actual controller and motor recommendations, qs180, maybe some of the motenergies, the zero z75-7r and -10 as well...
Would probably stay away from the torp/sotion offerings since the claimed ~10-13kg seems oddly low for something that has a claimed output of 50 odd kws. Controllers would probably boil down to the already mentioned fardriver and kelly, as well as possibly sevcons, though that really depends on your motor...

There sadly arent really many small, high voltage motors that can take a lot of power and would fit into something like a dirtbike/motorcycle...Would love to see some ~300-400v offering from the likes of qs but I suppose there isnt much market for it...

The main constraining factor in a build like this will be the battery, I would probably be better to pick out a frame and design a battery around it, then just simply going for the largest controller and motor that can be powered by said battery. Would be a shame to have a motor and controller capable of much more than is able to be supplied by the battery...
Click to expand...
Thanks for the advice, thinking about the qs180 and the fardriver, racing edition 125k, better overkill and don't use then to less.
Going to sleep a night an tomorrow order something.
 
Dailyride said:
Thanks for the advice, thinking about the qs180 and the fardriver, racing edition 125k, better overkill and don't use then to less.
Going to sleep a night an tomorrow order something.
Click to expand...
Again I would recommend at the very least figuring out what frame youre going to use before ordering absolutely anything...
 
A zero motor could probably work, there was some motor type Motenergy you could check out. I don’t have experience with HV and probably won’t except to try and figure DC fast charging. It’s too easy to get hurt if you have a brain fart while building— I’ve gotten shocked on 72v with sweaty fingers. I’d prob go with a suitable offering from QS Motor as their stuff tends to be severely underrated.
 
Dailyride said:
Lol, thanks for pushing it down instead of giving some advice:)
Click to expand...
I gave you advice, you just don't seem very eager to listen to it. Hey, you can disagree all you want, but those are the facts. If you can tip the scales at below 120kg with a ~6.5kWh battery and a 60kW powertrain based on QS180, all of my hats will be off to you.
 
thebes said:
Would probably stay away from the torp/sotion offerings since the claimed ~10-13kg seems oddly low for something that has a claimed output of 50 odd kws
Click to expand...
Anyone heard something about the real world power of watercooled FW20 from sotion?
They claim 100Nm with 1800pA
Probably you can run it without a reduction gear. But you will need a big chainring on the rearwheel
 
dominik h said:
Anyone heard something about the real world power of watercooled FW20 from sotion?
They claim 100Nm with 1800pA
Click to expand...
I thought that it was a low kv motor, but maybe not if it is only 100Nm at 1800pA. I think that the sotion gts35 would be more interesting anyway with gear reduction and it seems to have high kv. But I dont have any experiance with any of them though. I wouldnt consider running without a primary reduction..
 
That was the bigger FW30
Fw20 is a 15kg 100V Motor with 10krpm and claimed 80kW peak power.
 
now my brain is going nuts lol,

Motor Options:​


  1. QS180 – High-performance mid-drive motor,
  2. TM50 – Less common, but mentioned in high-power builds
  3. Motenergy motors – ME1507, ME1616, etc. — industrial-grade motors
  4. Zero Z75-7R / Z75-10 – From Zero Motorcycles, compact and powerful
  5. Sotion FW20 – Water-cooled, 15 kg, 10k RPM, rated up to 80 kW peak
  6. Sotion FW30 – Larger version, also rated up to 80 kW
  7. Sotion GTS35 – High-RPM motor with built-in gear reduction
  8. Torp motors – Lightweight with high claimed power, but real-world performance is debatable


🔧 Controller Options:​


  1. Fardriver ND961800 – 96V class, ~76 kW peak
  2. Fardriver ND961800 Plus – Upgraded version, ~105 kW peak
  3. Fardriver ND961800 Plus Racing – Highest version, ~125 kW peak
  4. Fardriver ND1081800 – Higher voltage version, supports up to ~108V nominal
  5. Kelly KHS series – High-voltage (up to 360V),
  6. Votol EM-550 – More mid-range, usable with lower voltage systems
  7. Semikron SKAI2 – 450V/300A (135 kW), industrial-level —
  8. Sevcon controllers – Flexible, powerful, but more advanced to set up

Still thinking about, the fardriver controllers, and the qs180 . i like the fardriver controllers a lot costwise. and also voltage wise, i don't like to go over 120v. I think its a bit to dangerous, i know 120v is also dangerous, but seems a lot saver then 320v-340v or something. So now im a little confused, i think for the controller, the fardrivers are the best, but for the motor i still don't know what to choose, weight and performance wise. i would like to keep the weight also down.

Any combo suggestions incomming?
 
Fw30 is over 30kg and only 15kw rated 2,5krpm, to heavy for a dirt bike
 
Dailyride said:

Motor Options:​


  1. QS180 – High-performance mid-drive motor,
  2. TM50 – Less common, but mentioned in high-power builds
  3. Motenergy motors – ME1507, ME1616, etc. — industrial-grade motors
  4. Zero Z75-7R / Z75-10 – From Zero Motorcycles, compact and powerful
  5. Sotion FW20 – Water-cooled, 15 kg, 10k RPM, rated up to 80 kW peak
  6. Sotion FW30 – Larger version, also rated up to 80 kW
  7. Sotion GTS35 – High-RPM motor with built-in gear reduction
  8. Torp motors – Lightweight with high claimed power, but real-world performance is debatable


🔧 Controller Options:​


  1. Fardriver ND961800 – 96V class, ~76 kW peak
  2. Fardriver ND961800 Plus – Upgraded version, ~105 kW peak
  3. Fardriver ND961800 Plus Racing – Highest version, ~125 kW peak
  4. Fardriver ND1081800 – Higher voltage version, supports up to ~108V nominal
  5. Kelly KHS series – High-voltage (up to 360V),
  6. Votol EM-550 – More mid-range, usable with lower voltage systems
  7. Semikron SKAI2 – 450V/300A (135 kW), industrial-level —
  8. Sevcon controllers – Flexible, powerful, but more advanced to set up
Click to expand...
Why does this read like you shoved this thread into chatgpt...? Especially considering that this text editor doesnt have native insert support for "—"...😅

Anyways,
Dailyride said:
Still thinking about, the fardriver controllers, and the qs180 . i like the fardriver controllers a lot costwise. and also voltage wise, i don't like to go over 120v. I think its a bit to dangerous, i know 120v is also dangerous, but seems a lot saver then 320v-340v or something.
Click to expand...
Just to be clear either of these are easily enough to kill you if youre not careful!

Dailyride said:
So now im a little confused, i think for the controller, the fardrivers are the best, but for the motor i still don't know what to choose, weight and performance wise. i would like to keep the weight also down.

Any combo suggestions incomming?
Click to expand...

If youll let me, Im going to continue being annoying about your battery and frame choice haha. Lets assume you go with 28s, which is ~102v nominal ~117v full charge, mostly thats what most of the previously mentioned motors can take rpm wise. To hit that ~60kw goal youd need 575 amperes, at the very least using something like p42as that would be at the very least 28s20p or 540 cells, which comes out to 37kg for just the cells. The total battery weight with all the connections, bms, wiring etc would most likely be over 40-45kg. Thats not something thatll just fit into any old 250 or hell even a 450 frame.... Now admittedly you could be using better cells such as some of the new tabless ones but they are all still very expensive and dont provide that much of a noticeable increase in performance, the pack would still be something like 14-16p. I implore to you at the very least give some thought as to what bike youre going to be converting...

Now to answer your actual question, the hv kellys arent bad but there are not really any suitable and small motors, they are more intended for light evs/cars. If you go with a zero motor you should probably pair it with a sevcon since they are deisgned around one another (and this somewhat applies to motenergy as well). Fardrivers are for whatever else is left, qs, etc. The nd108 series is basically double the price of the nd96s (at least for me here in the US pre tarrifs) with only a slightly higher max voltage, it doesnt seem particularly worth it unless you have money to burn. Theres also not much point to the "racing" versions of either of these since you wont be able to utilize the higher current input particularly well anyways.
 
Dailyride said:
no budget in mind really. but i just watch the prices.
Click to expand...
So is that you have a more or less unlimited budget or is that I'm never going to actually build this thing so it doesn't matter. My point is having some vague idea before you start picking parts with reckless abandon to how much it will cost, you could easily end up spending more than a Varg.

Just feels like one of those project ideas I've seen a lot, big ideas with no precise goals that in the end is just all planning and never goes anywhere.
 
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