My1020 3000W Pitbike - budget build

[Braddudya]

I bought a couple of ktm 65sx dirt bikes for next to nothing. I am converting them to electric. One of the bikes is significantly smaller. It's bigger than those Razor toy bikes but it's small even for a Pitbike!

For the small bike I don't want to spend tons of money. I picked up one of these kits on Amazon for $199 shipped.

https://m.vevor.com/brushless-dc-motor-c_11227/vevor-electric-brushless-dc-motor-kit-72v-3000w-4900rpm-motor-controller-go-kart-p_010307620598?utm_source=google&utm_campaign=16509130710&utm_term=&gclid=CjwKCAjws--ZBhAXEiwAv-RNL5JEYRDP-gUbBKgSMCgRMzZiaw8LZ9m41Fo0NPQHCIjjPOzgtQLupRoCULQQAvD_BwE

I know this motor is small for this application but for this bike I am mainly hoping it can be fun for my 120lb girlfriend to cruise around on.

So far I have the smallest 9 tooth 420 sprocket I could find on the motor and the biggest 57 tooth rear sprocket I could find. I am trying to get decent torque moreso than top speed.



Right now I am just mocking up the motor and controller. The controller is huge so there are only a couple of places to put it.





The motor mount is 3D printed for now. I can show more pictures once I have it more dialed in. I am going to see how it works in actual use. If it can't hold up I also have a CNC machine and can make it out of aluminum. I am always impressed with what can be done with creative designs and 3D printing though!

I am also building a 10ah 24s LiFePO4 battery with ant bms. It will be housed in a 3d printed case that will probably mount like a saddle where the gas tank previously resided.

Any thoughts on this project? Concerns? Criticisms? Have at it!

 

[skeetab5780]

Sub'd Nice little build!
Those Vevor kits are pretty powerful and fun for the price! They suck down the power use a strong battery!

 

[Braddudya]

Sub'd Nice little build!
Those Vevor kits are pretty powerful and fun for the price! They suck down the power use a strong battery!

Its funny that you should comment on this build. I was actually just watching a bunch of your videos last night trying to learn more about using a my1020 in a larger frame build like this! It looks like it works well enough if you can get a good gear reduction. It will also help that these ktm bikes have such small wheels. My biggest concern now is that I fear the motor wont last very long. It seems like these higher power 1020's get chewed up ridiculously fast.

 

[skeetab5780]

Sub'd Nice little build!
Those Vevor kits are pretty powerful and fun for the price! They suck down the power use a strong battery!

Its funny that you should comment on this build. I was actually just watching a bunch of your videos last night trying to learn more about using a my1020 in a larger frame build like this! It looks like it works well enough if you can get a good gear reduction. It will also help that these ktm bikes have such small wheels. My biggest concern now is that I fear the motor wont last very long. It seems like these higher power 1020's get chewed up ridiculously fast.

That is funny! Ya in my Voloci build with the MY1020 motor I have no way to cool the motor down, it seems to get pretty hot with zero air flow, with the 65a controller that it comes with it puts out 5000w continuous

I like the Heat sink you have on yours but I would not run this motor on any real sized dirt bike its just too small, maybe a QS138 motor with the reduction built in or a D9000 Denzel you will need about 15,000watts for these builds to have similar fun

 

[Braddudya]

I like the Heat sink you have on yours but I would not run this motor on any real sized dirt bike its just too small, maybe a QS138 motor with the reduction built in or a D9000 Denzel you will need about 15,000watts for these builds to have similar fun

Agreed. The 65sx though is a kids bike. Its about the same weight (minus the drivetrain) and actually smaller than my fat tire ebike!



Its pretty small so I assumed this little motor should still be fun in it....as long as it can hold up!

I also do have the advantage of a very small tire, which will help reduce the required torque to climb a hill.

 

[Braddudya]

I finished the motor mount for the first real test.


Used M8 threaded brass inserts for all of the mounts. This print is also 50% infill with extra thick walls. It is very rigid and robust for a plastic part. We will see how it fares







I went ahead and threw the battery together and wired it up for a quick test. Video below.

https://streamable.com/gwkhxw

I had to rewire to get it to spin in the opposite direction but it seems to be working!

The only real issue I had was the red switch on the throttle. Not sure what it is supposed to do but when I switched it the wiring for the switch essentially exploded and blew out smoke. I just connected it to the wires on the controller which matched the colors. Kind of a stupid move considering I didn't know the function of the red switch haha but it happens. Anyone know what it is for? Everything else still works fine as far as I can tell.

 

[skeetab5780]

Really clean motor mount! clever idea rather than just welding a bunch of metal...Keeps it close to the pivot

Where did you get that sprocket? I had trouble sourcing larger sprockets for this motor

 

[Braddudya]

Really clean motor mount! clever idea rather than just welding a bunch of metal...Keeps it close to the pivot

Where did you get that sprocket? I had trouble sourcing larger sprockets for this motor

Thanks. That was the goal. It's also much easier to iterate than cutting and welding. I am actually already on version 3. One other big advantage is that I can adjust the sprocket height with shims if I need to. I'm no expert on how the chain should be positioned so I tried to copy the stock form as close as possible and left room for adjustment!

It took me a long time to find out a good sprocket for this motor. It seems like 99% of these things go into those little razor toy bikes.

https://cart.electricscooterparts.com/9-tooth-10mm-double-d-bore-sprocket-for-40-41-and-420-chain

In reality the 420 chain is way overkill but switching the rear sprocket to a smaller chain would require custom machining. That is an option but the little $14 sprocket seemed like a good place to start.

 

[skeetab5780]

Really clean motor mount! clever idea rather than just welding a bunch of metal...Keeps it close to the pivot

Where did you get that sprocket? I had trouble sourcing larger sprockets for this motor

Thanks. That was the goal. It's also much easier to iterate than cutting and welding. I am actually already on version 3. One other big advantage is that I can adjust the sprocket height with shims if I need to. I'm no expert on how the chain should be positioned so I tried to copy the stock form as close as possible and left room for adjustment!

It took me a long time to find out a good sprocket for this motor. It seems like 99% of these things go into those little razor toy bikes.

https://cart.electricscooterparts.com/9-tooth-10mm-double-d-bore-sprocket-for-40-41-and-420-chain

In reality the 420 chain is way overkill but switching the rear sprocket to a smaller chain would require custom machining. That is an option but the little $14 sprocket seemed like a good place to start.

Wow I will be alright...that is actually the same place I bought my sprockets for this motor, and I just got my 415 chain from them also!

 

[Braddudya]

Now that it's spinning I am waiting on some pvc shrink sleeves for the batteries before I can ziptied mount them for initial testing!

Got one other important thing done in the meantime. The chain slider was completely worn through to the point that I had to cut the bolt off with a grinder to remove it. It was half cut through by the old chain already!




The beauty of designing a new 3D printed slider is that it only costs me about $0.60 to print so I can just replace it more regularly even if it doesn't last very long. It is only one bolt to swap it out.



I am hoping to test ride it this weekend! Should be very interesting to see how it all works. It feels good on the test stand but the real test will be with my 6'2" 210lb butt on the seat.

 

[skeetab5780]

3d printed slide looks nice! I am slightly larger than you... so it will still pull you around nicely!

 

[Braddudya]

3d printed slide looks nice! I am slightly larger than you... so it will still pull you around nicely!

Good to know!

Anyone know what these wires are for?



They are unlabeled. And I know they can be for learning functions or reversing the standard direction. I haven't tried unplugging them yet. I can't find any documentation for them online.



I am also unsure what indicator light means. The is a brake lamp plug already... So what is an indicator? It can't be turn signals because it's just 2 wires.

 

[Braddudya]

Did some riding today!

https://streamable.com/jq0lw7

Seems to work as expected! There is one big issue though. On take off I have to baby the throttle to the absolute lowest degree possible or it stutters like crazy. Once I am up to some speed I can hammer down no problem, but on the start it's hard not to stutter the motor constantly.

I had to swap 2 hall sensors and then swap the phase wiring around to get the direction right. So I did try more phase wire combos to see if I had it wrong but it is clear that only one is right.

On the hall wiring I swapped blue and green and on phase I get the smoothest running and the right direction with yellow and green swapped.

Any ideas on how to fix this?

 

[Braddudya]

I swapped in a flipsky 75100 Vesc to replace the old Chinese controller. Long story short it took quite a bit of messing around but I got it running quite smoothly. Now the only issue is that it is very slow off the line. It has good top end but the acceleration is like half. The 75100 seemed too good to be true and I think it is too good to be true. I have now ordered a 75200. I don't think it will be wild performance with the 200 either but I think it will be fun and I can get started on my second Pitbike conversion which will be much more powerful and but non Vesc.

If anyone is a VESC wiz I would love to learn more. It seems like the future of the DIY EV scene.

 

[MorbidlyObeseKoala]

Nice work with the vesc. There are some settings with throttle ramping that can change acceleration BUT I really think that little guy can't handle a bike of that size and the amperage needed. On the eSK8 forums, people have pulled up to about 2kW but it needs additional heatsinking and can be tough to tell if you are hitting amp limits without the data logger running in real time.

Interested to see how that 75200 performs. The vesc controllers can do all kinds of wild additional stuff that most other controllers have not implemented. (i.e.- data logging, speed dependent lighting, adjustable regen, etc.)

 

[LCLabs]

Ill be watching as I just picked up a similar-sized pit bike. When you say run smooth for the VESC, was it a hall effect issue?

 

[Braddudya]

Nice work with the vesc. There are some settings with throttle ramping that can change acceleration BUT I really think that little guy can't handle a bike of that size and the amperage needed. On the eSK8 forums, people have pulled up to about 2kW but it needs additional heatsinking and can be tough to tell if you are hitting amp limits without the data logger running in real time.

Interested to see how that 75200 performs. The vesc controllers can do all kinds of wild additional stuff that most other controllers have not implemented. (i.e.- data logging, speed dependent lighting, adjustable regen, etc.)

I am sold on VESC as the future of EV controllers. I am less impressed with the 75100. It was only $100 so I guess I shouldn't expect much. I was pulling 2.5kW but only for about 6-8 seconds before it would jump from 30c to 83c and thermal throttle. It's too slow at 70a and it overheats at 100a so it's not useful for this project.

For $200 on Amazon the 75200 seems to be 10x the value. I haven't used it yet but I received it last night and it's beefy in a good way compared to the 75100. It might still overheat but we will see.

Ill be watching as I just picked up a similar-sized pit bike. When you say run smooth for the VESC, was it a hall effect issue?

I don't know what the issue is. These my1020 motors seem to be so poorly designed and/or constructed that most quality controllers struggle to work with them. If I were advising someone else on what to use for a conversion like this I would just go with the 200a trapezoidal controller from Kelly. It seems to work easily and reliably with these. I am using the VESC because I like the idea of the open source project and want to learn how to use it. I do t think this hardware is a great fit for the project compared to the Kelly

 

[Braddudya]

The Flipsky 75200 is awesome and really completed this build. Off the line acceleration still isn't crazy but it's strong and smooth. I still have some tuning to do but it already goes much too fast. If I can find a deal on an even bigger rear sprocket I will probably swap that, otherwise this project's major components are complete.

Now I am going to print a new version of the battery holder that incorporates mounting for the bms as well as a cover plate to seal the whole thing up. I'll update with photos as it gets buttoned up!

 

[harrisonpatm]

Looking to hear details on how well the 75200 worked for you. Considering it for my next build, and I have no programming experience, so I'm hoping I can manage it anyway. I hear lots of good things about it though.

 

[Braddudya]

Looking to hear details on how well the 75200 worked for you. Considering it for my next build, and I have no programming experience, so I'm hoping I can manage it anyway. I hear lots of good things about it though.

It isn't really programming as in coding or anything. It is just a graphic interface with tons of options and values that can be set. I would say difficulty to get a motor setup and working using the config wizards is like a 3 out of 10. Just follow a guide. The difficulty of figuring out what every single parameter means and how to perfectly tune a motor to its best performance is like a 9 out of 10 haha 10 being brain surgery. I am no expert but this was my first time using VESC and I can say it is totally doable for a patient newbie who is good with google and attention to detail.