Need advice on electric dirtbike

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Blackdavid   10 µW

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Need advice on electric dirtbike

Post by Blackdavid » Feb 17 2019 12:46pm

Hello guys, i'm new to the forum 😁
I am currently gathering intel to build my own E-dirtbike. I have a KTM SX85 complete bike but no engine, that I got from my local junkyard..anyways:
First question:
What motor should I use?
Basically I want the bike to be powerfull, i dont care about top speed, let it just be 40mph i'm okay with that.. I just was it to have torque and acceleration, its a pretty lightweight bike(66 kg with engine,dry)
So I think about 15kws should be good?
Also, how about two Turnigy rotomax 150cc? I can make my engine mounts and pulley system pretty easy at home since I have access to a mill, and lathe too.. but would that motors hold up?

lionman   100 W

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Re: Need advice on electric dirtbike

Post by lionman » Feb 17 2019 10:16pm

Id be more inclined to go with a purpose built solution. The Rotormax while being large and powerful brush less motor, isn't really designed for the kind of torque that you need in a dirt bike. You'll probably find you don't need to match the ~25hp of the original 85cc 2 stroke engine to get similar or better low end performance. An electric motor will deliver a lot more torque from the get go.

Id look at something like this kit

https://www.electricmotorsport.com/ev-p ... ystem.html

or a slightly cheaper cheaper option is one of the more powerful motors/controllers from these guys.

http://www.cyclone-tw.com/motor.html

SlowCo   100 kW

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Re: Need advice on electric dirtbike

Post by SlowCo » Feb 18 2019 5:05am

Blackdavid wrote:
Feb 17 2019 12:46pm
What motor should I use?
http://www.eastgem.net/d7500-k-1.html

markz   100 GW

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Location: Alberta Canada

Re: Need advice on electric dirtbike

Post by markz » Feb 18 2019 3:33pm

A few more options for ya

https://www.goldenmotor.com/
20kw with water cooling

http://cyclone-tw.com/motor.html
20KW spokes motor

Blackdavid   10 µW

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Re: Need advice on electric dirtbike

Post by Blackdavid » Feb 18 2019 5:10pm

Thank you all very much for the advices, but I'm more concerned about the import and shipping charges on those thing since i live in Croatia, and I suppose they're all USA?
Anyways, i found a company named Alien power systems that make pretty affordable motors, and I found they have an 18kw peak version, that a lot of dudes use on ebikes.. would that be a solution?
Keep in mind i can make all my supports,mounts and everything myself on the CNC, I also already have a KTM SX 85 frame available I picked up earlier this week. Putting one of those with a support bearing at the end would make it last anything long enough or it would be shot after 2 days? Most of the purpouse built kits are only a couple of kws, and since i'm used to the mental power a 250 two stroke makes as i ride one every day, I would like to at least have 10-15kw, with good torque. Also I would like to stay in a close budget for the motor since I'll be spending a lot for the batteries.. thanks for the help..

Grantmac   1 kW

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Re: Need advice on electric dirtbike

Post by Grantmac » Feb 18 2019 6:38pm

Pretty sure eastgem ships free worldwide and their motors are rated conservatively. Likewise QS has a "3kw" setup that people push past 15kw.

Alien stuff is usually quoting peak power with lots of airflow because they are RC designs.

lionman   100 W

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Re: Need advice on electric dirtbike

Post by lionman » Feb 18 2019 9:31pm

What is the reason for wanting to fit an RC style motor to a dirt bike?

They are designed more for high speed than high torque, which is usually evident in the size of the output shaft. To get around this you need some sort of gear reduction system which will just complicate the design and make the bike more susceptible to mechanical issues, and potentially take up valuable battery space. You want as few moving parts as possible in my opinion.

You will be better served with more robust motor like a Cyclone,Golden Motor or Denzel as linked above.

vagosofron   10 W

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Re: Need advice on electric dirtbike

Post by vagosofron » Feb 19 2019 2:47pm

lionman wrote:
Feb 18 2019 9:31pm
What is the reason for wanting to fit an RC style motor to a dirt bike?

They are designed more for high speed than high torque, which is usually evident in the size of the output shaft. To get around this you need some sort of gear reduction system which will just complicate the design and make the bike more susceptible to mechanical issues, and potentially take up valuable battery space. You want as few moving parts as possible in my opinion.

You will be better served with more robust motor like a Cyclone,Golden Motor or Denzel as linked above.
My guess is that he is looking to buy from Europe, like i do, because he will have to pay huge amount of customs taxes if he buys from US or China.

lionman   100 W

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Re: Need advice on electric dirtbike

Post by lionman » Feb 19 2019 9:56pm

Surely there are European suppliers??

Here is a Golden Motor retailer in Lithuania
https://www.miromax.lt/en/m-6/c-39/c-45 ... o_products

vagosofron   10 W

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Re: Need advice on electric dirtbike

Post by vagosofron » Feb 20 2019 7:30am

lionman wrote:
Feb 19 2019 9:56pm
Surely there are European suppliers??

Here is a Golden Motor retailer in Lithuania
https://www.miromax.lt/en/m-6/c-39/c-45 ... o_products
There are, but not that many.
Edit. Now that i looked at that site, they have enough products for a custom built and reasonable prices. I don't know if they are reliable though.

Blackdavid   10 µW

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Re: Need advice on electric dirtbike

Post by Blackdavid » Feb 26 2019 1:31pm

Sorry for the late reply, been a bit busy..
So first I was thinking about RC motors because i cannot seem to find any other motor that gives that much power for that much money($500-ish , and 6kw and 10ish kw peak isn't nearly enough for me 🤷‍♂️

Gearing it down in some sort of gearbox isnt gonna be a problem since ive already tought of doing that anyways, and have a machine shop at my disposal..
My only concern with that kind of setup would be: is the motor gonna hold up? I would obviously support it in whatever way i could and make a forced cooling system if not even water cooled, but would that also be enough?
Other problem i have is I would need AT LEAST 35 mins drive time(since the races last about 30 mins every round), and i really DONT understand batteries.. but i could do two battery packs each at 35 min and swap them out obviously if its doable..

And at last, Yes the import charges and taxes would kill me getting a motor from the US or china, and there is an importer in Italy for the alien motors that could even make me a 5% discount on the price they ask..
Thanks for all the replies!

Grantmac   1 kW

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Re: Need advice on electric dirtbike

Post by Grantmac » Feb 26 2019 3:19pm

Seriously the QS3000 is ideal for your application and the controller supplied is likewise very powerful. Even a 25% tax would not significantly impact the difference in expense once you look at having to add a second stage of reduction.
Plus the battery to feed it for 30 minutes will be far more costly.

markz   100 GW

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Re: Need advice on electric dirtbike

Post by markz » Feb 26 2019 8:27pm

I would just buy from these guys if you get that 5% discount.
https://alienpowersystem.com/product-ca ... ss-motors/

Blackdavid   10 µW

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Re: Need advice on electric dirtbike

Post by Blackdavid » Feb 28 2019 5:12pm

I can't trust an RC motor breaking from stress in the middle of a race.. also, as I said before, there is nothing currently available at a normal cost for me at the moment, that would suit my needs...

Thanks for the help guys, I think i'll stick a 250 2stroke in it after all :thumb:

markz   100 GW

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Re: Need advice on electric dirtbike

Post by markz » Feb 28 2019 6:27pm

Blackdavid wrote:
Feb 28 2019 5:12pm
.
There is a company that makes a hub motor in Croatia, I just can't think of it right now because its been so long since the name has come up where I read it. Hmmmmm Greyborg comes to mind but thats a frame, ah a simple search with the term Croatia and CROMOTOR comes up! Thats the ticket, right there, if they are still selling their wares.

What about buying from the USED section on this forum?
What are your import tax rules on that?
I wanted to see if Croatia was apart of the EU, it seems it is, from 2013. I have no clue how them VAT taxes work, but if you buy within the EU you should be good to go right.

I got the list from Canada's GrinTech, the guy who keeps Endless Sphere alive and kicking.
https://www.ebikes.ca/dealers.html
Start contacting every company/person that is apart of the EU.
Greyborg d.o.o.
Ljubljanska 7
Sveta Nedjelja,
Croatia
zvonimir@greyb.org
www.greyb.org
Installs Kits? NO
Sells: Satiator




Electric Bike Solutions GmbH
Carl-Bosch Strasse 2
Heidelberg, Baden-Württemberg
Germany
info@ebike-solutions.de
http://www.ebike-solutions.de/
Installs Kits? YES
Sells: Cycle Analysts, Satiator, Direct Drive Kits, Geared Motor Kits, Stokemonkey, Batteries, LED Lights, DC Converters, Torque Arms
Sells:
Ecopolis Italia
via Primo Maggio, 27
CREMONA, ITALIA
Italy
info@ecopolis-italia.com
Installs Kits? NO
Sells:
Petar Delchev
Major F. Gortalov 1
Kazanluk, Stara Zagora
Bulgaria
petar.delchev@gmail.com
www.ofer.bg
Installs Kits? YES
Sells: Cycle Analysts, Batteries

Blackdavid   10 µW

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Re: Need advice on electric dirtbike

Post by Blackdavid » Jul 29 2019 6:13am

Hello guys, thanks for all the replies. So i have finally settled on a hub motor at last, given that i have found the perfect frame for the dirt bike, and i will have much more space for the batteries that way. Anyways, i am still looking for a motor, i have found a company called qs motor, but it seems they are american based? I found the 8kw hub from then, that would be okay since its rated at about 16kw peak, and 12kw constant. My questions are, can any hub motor fit a motocross wheel? I think there 19 back and 21 inch front. Can you give me some advice of a hub motor what would fit, and one that doesn't have less than 8kw? Thanks a lot

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efMX Trials Electric Freeride   100 kW

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Re: Need advice on electric dirtbike

Post by efMX Trials Electric Freeride » Jul 29 2019 7:30am

if the bike is for motocross track type riding with jumps and bumps etc a hub motor would be a poor choice due to heavy un-sprung weight of the motor rear wheel.. and rear bias weight distribution of the bike instead of centralized weight of mid drive.. maybe check out Deller, they make electric motorcycles and recently did a ktm85 conversion.. also check with Mammoth ebike, the also makes electric dirt bikes and may have motor suggestion.. search this forum, YouTube, facebook, etc for those emoto companies nearer to your country/ location.. look for Sur-Ron dealers near your location, they are popping up everywhere and may be able to help you locate other EV resources near you.. another example : elektropogon.com
some ride & sk8 videos:
metacafe.com/channels/NATAS666DAMIEN
http://www.youtube.com/natas666damien
i have nothing for sale.. :)

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