KX100 Electric Pit Bike

[DonCox]

I built this for a friend in about 6-7 weeks. It started life as a 1991 KX80, was converted to big wheels some where along the line. My friend put new tires on it and had the suspension gone thru. Gave it to me. Now after he get it back, he is going to ride it a bit and the tear it down and powder coat the frame after all the work.
@Mark911 challenged me to a PIT BIKE race, but I think the owner is going to take it too soon, he is excited.

After some research I found Electro and Company (ElectroBraap) for the hardware and controller programming. They have bolt on kits for other pit bikes, but not for this model bike, so I had to build my own mounts and battery. They have a beautiful kits for 2002-2018 YZ85, and another kit for 2002 - 2016 KTM 65 SX. But they sell motor-controller-wiring - programming kits that work great.
We purchased a QS 138 70H V3 motor Controller kit, with there (Electro) programming, a wiring harness, with throttle and switches. I comes with a Chinese display that is cute, but not real useful. This kit made the conversion sweet and much simpler.
I'll put a few pics in here, but I took a lot and videoed a lot. If you want all of them, EM me and I can find a repository for all of them or a CD or USB stick. I also have the templates for the motor mounts and battery box. I am going to get some of these water-jetted or Plasma cut, and the battery box case we can talk about it f you are interested. I chose Molicel 21700 cells in a 20S8P config. The motor /controller only draws 210-250A, but for longer ride time I went to the 8S config. I used an ANT 300A Smart BMS. Man that is sweet also. I got most everything from ElectroandCompany.com, except the cells and battery cell holding brackets.
The Bike weighs 175lbs. the motor gear reduction weighs 28.5lbs, complete battery 30lbs. It is so fun to hop on and go, but in Warp mode (15KW, 20HP) the front wheel isn't on the ground very much. It has 3 speeds. ElectroandCompany.com added their programming and it is so plug and play. Th ANT BMS is so smooth and you can look at all the Battery vitals.
Cost is in the range of $3000 to 4000 depending on buying a battery or building a battery. (Not including the donor bike) Motor / controller $1300, Battery parts $1500 ( that's including a 15A charger. Electroand Company gets somewhere near $2300-2500 for there same size SLR3.2 with charger, and that is a good price, knowing how much work goes into one. Theirs wouldn't fit in my frame.) And a motor mounting kit and battery box maybe $300 to 400.
The bike didn't look symmetrical with only one radiator shroud, so I found a 2020 KLX110 bike had a mock radiator shroud. So I got one and it fit with a little work. Definitely looks more contemporary.

 

[Philip]

A pretty cool dirt bike electrification service from @ElectroBraap and @Mark911. Just BYOB (bike).

 

[Bob Casper]

Don, Another great project . Can't wait to see it up close.

 

[Sash]

Nice build!

 

[testus191]

@DonCox where did you purchase the Molicel cells?

 

[DonCox]

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liionwholesale.com

These guys are quick and good price. I have bought from them multiply times. Don't take them all, I have another order to put in soon...

 

[testus191]

Search Results

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liionwholesale.com

These guys are quick and good price. I have bought from them multiply times. Don't take them all, I have another order to put in soon...

It’ll be awhile before I’m ready to buy so no worries!

Have you ever used IMRbatteries or 18650batterystore?

Also, how are you doing your cell connections?

 

[DonCox]

You asked about how am I doing my connections. I tried to use a couple of spot welders, but I couldn't get enough penetration because the bus bars I wanted were too thick. So I got some good soldering tools and have used that on all 4 battery pack I have built. The first 3 were with the Sony VTC6 cells 18650 size, and the last one was Molicel 21700 P42 cells.
They have all been used in MX motorcycle applications. I have used Lead tin solder because it has a lower melting temp so I can get on and off the cells faster with the heat. I scuff the cell ends with a small grinding wheel to help the flow and bond. I use a 480 degree soldering iron, and the solder melts at 380 degrees. I make the bus bars from #12 romex (2mm diameter) for the main buses, and 1mm copper for the cell connections.
We tested the 1mm copper wire and it takes about 100A. I have used the 2mm copper wire for a 400A fuse on another dirt bike.
I hope this gives you the info you needed.
I always use the LiIonWholesaler to source my cells.

 

[testus191]

@DonCox thanks for the insight! I certainly wish there were a better more reasonably priced option for the DIY crowd for this. The pulse arc welders are expensive! I have a Malectrics spot welder that I have not used much, but I’m not confident even using the nickel copper method will work all that well. I guess I’ll find out when I can find some time to test it on a small 12v pack.

Look up a guy named Gary Little, owner of Vectrek karts. He has a Sunstone welder and offered to weld my pack for a very reasonable price. He’s in Georgia I believe.

https://vextrek.com/

 

[Vextrek]

@DonCox
Look up a guy named Gary Little, owner of Vectrek karts. He has a Sunstone welder and offered to weld my pack for a very reasonable price. He’s in Georgia I believe.

https://vextrek.com/

Thanks for the shout out. Vextrek, LLC is located in Augusta, GA and we have a Sunstone Pulse Arc welder which can spot weld pure copper to cylindrical lithium ion cells. We can spot weld packs in a variety of configurations so let us know if you are in need of a replacement back for your electric dirt bike. We are not authorized to ship lithium battery packs yet but we can deliver to customers in the Augusta/Atlanta, GA area.

Background: We started out as an electric go kart company but realized that our spot-welding capabilities may be of value to other markets such as electric dirt bikes. Our go kart battery pack consists of INR Samsung 25R cells ("18650") and is configured as 22S/21P (80V nominal and 52 aHrs). The pack utilized the standard plastic cell holders and were connected with .25mm thick pure copper. We routinely pull 400-500A with this pack and we recently hit 100mph at a local dragstrip. Attached below are photos of some lithium packs we have spot welded using .25mm thick pure copper.

Here is our Facebook Page: www.facebook.com/VenomKarts/

Gary Little,
Vextrek, LLC

 

[DonCox]

I've built 2 more KX's, another 1991 KX80 and a 2008 KX100. same controller on the KX80, but a EM-260SP/2 on the 2008. I am going back to the EM150SP/2 on the KX100, 200a is more than enough for that size bike. I made the KX100 street legal here in Arizona. I'm calling it my KXesla.
here are a few pics.

 

[Redwolf]

Those look great, almost makes me wish I had kids!

 

[Bob Casper]

Great build and even with new tires. Looks great

 

[alvin]

I have a KX100-C that I want to put the QS138 70H v3 in. I'm going to make it street legal and use it on the road. So I'm looking for some advice. It is my first bill so any help will be greatly appreciated. I'm wondering about the mounting bracket, how is the best way to approach this to make sure things line up properly.

 

[DonCox]

Hey, I’d be glad to help you. You are going to love the bike. I’ve built three KX 80-100’s with that motor and some full size dirt bikes too. Are you in Yucaipa, if you want to come out here to Lake Havasu, you can ride mine, and ride my YZ with the same motor, and see how it’s done. Do you have the motor controller kit yet.
Here is a YouTube of it racing the PitBike race at the Pala National in May this year.

I could build the mounts onto your frame for the motor, controller, and battery.
I would recommend getting your kit from ElectroandCompany.com. It comes ready to ride. Plug together and play, motor, controller, wiring harness , throttle with switches, and programmed ready to ride.

 

[alvin]

Hey, I’d be glad to help you. You are going to love the bike. I’ve built three KX 80-100’s with that motor and some full size dirt bikes too. Are you in Yucaipa, if you want to come out here to Lake Havasu, you can ride mine, and ride my YZ with the same motor, and see how it’s done. Do you have the motor controller kit yet.
Here is a YouTube of it racing the PitBike race at the Pala National in May this year.

I could build the mounts onto your frame for the motor, controller, and battery.
I would recommend getting your kit from ElectroandCompany.com. It comes ready to ride. Plug together and play, motor, controller, wiring harness , throttle with switches, and programmed ready to ride.

View attachment 9004

I am in Yucaipa, it would be fun to make a trip over to Havasu. I have not got the kit yet. I'm just working on the plan at the moment but I do have the frame. I'll need to find some parts to make it street legal.

 

[DonCox]

That is a perfect donor. 2001-2013 is the newer plastics. Do you have the title on the frame. I made the street legal light kit for mine. Yea check with me to see if I am home and come on out here to try the bikes, they are so fun. I don't know how old you are to recognize these 2 guys riding the electrics. They have been around the motorcycle world for a long time. Both world Champions

The second bike is a 2017 KTM I did with the QS motor.
You know of any more KX's like yours? I have an older one, but I need 2 more with papered frames. Actually any one from 1991 to 2013 are the perfect ones to modify. I convert the 1991 to 2000 to newer plastics, using KLX110 tank plastics, since those early ones only had radiator shrouds on the right side.

 

[Glenl]

Hi Donald, i made it here. Nice builds, i'll soon create a topic of my own with the ride i'm converting to Electric. its a street legal version of a motorcross, like 17inch wheels and enduro tires. Last night i pulled the trigger on what kit to get.. So i ordered the qs138v3 with the EM200 controller. Getting a 72v 70AH battery with 200A BMS. should do 200continues 400 peak. So hopefully its enuf.
Regarding the gear and the electric i have some questions. Like there is a 15 T sprocket on the motor, and i currently have 51 rear so i will have to test this out once i get everything running. But i read online that this is a special shaft ? Have you had any issues fitting smaller gears on this shaft?
Second regarding the electronics, i got myself an entire kit that includes 676.45US $ 8% OFF|Qs 138 3000W V3 Mid Drive Motor 5500W Max Continue 72V 100KPH Conversie Kits Voor E fiets/E Motorfiets Van Siaecosys| | - AliExpress stuff for my lights etc. But one thing i am missing in some proper wire schematics for the main power breaker. That one u fit into the gas tank? I noticed you bridged those 2 contacts with a resistor? I read online that this can sometimes cause some current to keep going to the controller?
Greetz from Belgium
Glen

 

[DonCox]

Welcome to the forum Glen. The Kit you ordered is good for a smaller bike. Did you order the EM150SP/2 controller, or the EM200? The ...SP/2 is there newer line of controllers. With all the EM controllers, the motor max speed is about the same. Just how fast you get there, more Amps is faster. On the KX100 16" rear tire, and 15 and 49 sprockets, top speed is about 55MPH . What bike are you putting this on?
You will see, that if you don't have the surge resistor on the Master contactor or Master ON/OFF switch , it will arc every time you turn the switch on/off. It will burn up some switch's. Here are 3 pictures. One is the DC to DC converter I use, because it has a soft start circuit, and here is a overall schematic , and one is the wiring to the EM 200SP controller.

 

[Glenl]

Thanks Don, i got the EM200-2SP + the wire harnass and everything i need to get 12v for lights and everything. Also including a display and some keycontact . But in this kit there isa relay but im not sure its strong enuf to serve as the relay to connect the main + to the controller.. See the image below.
So i'll be buying one of those power brakers, and bridge them like u did. -> https://www.amazon.com/dp/B099WKJPBD/?tag=sce0f-20
Could i use something like this?

The bike i'm converting is something thats chinese so not really familiar with what its a copy from.. The plastic parts look all similar to me.
It has 17inch wheels.