Chinese Pit Bike Conversion | Nucular 12F | LMX-Motor 60mm | 18s 16Ah LiPo

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Amaxophobie   1 mW

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Chinese Pit Bike Conversion | Nucular 12F | LMX-Motor 60mm | 18s 16Ah LiPo

Post by Amaxophobie » Oct 07 2019 2:39pm

Finally a new project!! :D

So after looking on eBay every now and then I finally found a suitable pitbike with broken engine that would fit my needs. On this model I especially liked the engine mounts as these are two straight arms facing forward. This makes it fairly easy to adapt new parts such as motor mount etc. I bought it for a bit overpriced 80€.

Here are a few pictures from the eBay seller:
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After receiving all the parts I built it up just to see if the bearings had to be replaced and everything was intact.
As Iwaited for my LMX-motor to be delivered I quickly modeled it up in CAD and 3D-printed a lightweight model with the original dimensions to find a suitable place in the frame.
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Afetr that I removed all the dirt and old paint from the parts and prepared it for a new paint.
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For the color I chose a matt black. After greasing all the bearings and putting everything together it looked only a bit less ugly than before :roll:
K1600_IMG_5375.JPG
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Stunt scooter conversion |AP 80100 | KLS 7218S | 23 kg
viewtopic.php?f=35&t=97391

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John in CR   100 GW

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Re: Chinese Pit Bike Conversion | Nucular 12F | LMX-Motor 60mm | 18s 16Ah LiPo

Post by John in CR » Oct 08 2019 9:11pm

Looks like a nice little donor for an e-conversion. If the swingarm is steel, I'd definitely weld the motor mount to the swingarm in front and below the pivot point. The purpose would be to eliminate chain issues and make it as quiet as possible, as well as obtaining the anti-squat attributes of motor attached to the swingarm. Plus it would give you more room for batts.

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Amaxophobie   1 mW

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Re: Chinese Pit Bike Conversion | Nucular 12F | LMX-Motor 60mm | 18s 16Ah LiPo

Post by Amaxophobie » Oct 17 2019 2:12pm

Yes, the swingarm is steel. I thought about mounting the motor under the swingarm too because of the chain tension but had to erase that idea due to lack of a welding machine. Another problem is that the motor would be very close to the ground and would easily hit obstacles in rough terrain.

Let's go on:

So the plan was to use 30mm x 30mm aluminium profile for the motor mounts and batteries. This makes it really easy to adjust lenghts without drilling new holes.
Aluminium profile.jpg
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I took measurements from the wooden motormount and modelled it in CAD. I made a long hole on top because i wasn't sure about the exact position and wanted to have the opportunity to slide the motor back and forth until I was happy with it.
Motormount CAD.png
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Later that week it was then CNC milled out of 7075 aluminium. Below is a quick test fit with the motor which finally came in the mail that day.
K1600_IMG_6010.JPG
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Next step was to fit a 219 chain ring on the original rear hub. The bike came with a 420 chain ring mounted which inner diameter was slightly smaller than the diameter of the 219 go-kart chain ring I ordered.
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So I made an adapter that mounts on the original hub with 4 M8 screws and had 6 x M6 threads for the 219 chain ring. The difficulty here was that the motor couldn't stick out more to the side, so I had to make the adapter as thin as possible to maintain a straight chain line. Limiting factor was the head height of a M8 Bolt (8mm). After searching the internet I found M8 screws with very thin heads used for break discs on motorcycles. Perfect!!
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Adapter.png
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And after waiting two more days the adapter was also CNC milled out of 7075 and fit nicely and snug on the hub.
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Last edited by Amaxophobie on Nov 02 2019 12:13pm, edited 1 time in total.
Stunt scooter conversion |AP 80100 | KLS 7218S | 23 kg
viewtopic.php?f=35&t=97391

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Amaxophobie   1 mW

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Re: Chinese Pit Bike Conversion | Nucular 12F | LMX-Motor 60mm | 18s 16Ah LiPo

Post by Amaxophobie » Nov 02 2019 1:14pm

Let's go on with the battery housing:

With the 30x30 aluminium profile and the help of 90 degree connectors I made up a simple L-shape cage.
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CAD.png
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Batteries will be 3 x 6s 16Ah Multistar with which I am pretty happy. I already used them on my kick-scooter project and in terms of size and weight (1,5kg each) as well as performance (max. 0,02V cell drifting) they are just great if used with 6C constant and 12C peak (they are claimed with 10C constant and 20C peak).
K1600_IMG_6008.JPG
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I was so on fire to try this thing out but sadly the nucular 12F I ordered was already shipped but not delivered. So I soldered on new connectors to the motor and connected my trusty VESC6 in unlimted mode. With a lot of duct tape I secured two of the batteries (VESC is only 12s) and the controller. Only thing missing was connecting the two 219 chains I ordered and trimm them till they fit. And after carrying this heavy thing down my apartment stairs (I live in first floor) I finally took it for a first, short spin.
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Here is a screenshot of a video so you can see the size of this tiny bike:
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Of course the power with 160A phase and 120A battery was ... let's say not surprising. But it gave me a rough idea of the handling and feeling of this small bike. With 12s and 14/63 gearing it went 48 km/h or 30 mp/h with okay acceleration.
Stunt scooter conversion |AP 80100 | KLS 7218S | 23 kg
viewtopic.php?f=35&t=97391

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boars   10 W

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Re: Chinese Pit Bike Conversion | Nucular 12F | LMX-Motor 60mm | 18s 16Ah LiPo

Post by boars » Nov 05 2019 8:19pm

Oh wow, my sense of scale was hugely out with this bike - I didn't realise it was so small.
I then went back through your pics and paid more attention, it's bleeding obvious when you look at all the other objects like chairs.

I really do only see what I want to see haha :mrgreen:

What a cool little beast though, looks like a bunch of fun!

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Amaxophobie   1 mW

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Re: Chinese Pit Bike Conversion | Nucular 12F | LMX-Motor 60mm | 18s 16Ah LiPo

Post by Amaxophobie » Nov 06 2019 3:17pm

Don't worry, that's not the first time I heard that sentence :lol:

The size is right between a normal bike and a pocket bike. It has a seat height of about 780mm which actually makes it quite comfortable to sit on. As I'm about 1,90m tall I look a bit like a grasshopper while riding this thing but thats okay. The bike looks funny and me on it too so thats a perfect combination 8)

Here is the small video of the first ride I took the screenshot from.
Don't expect anything. It's just driving in a circle and testing the brakes...

Stunt scooter conversion |AP 80100 | KLS 7218S | 23 kg
viewtopic.php?f=35&t=97391

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SlowCo   100 kW

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Re: Chinese Pit Bike Conversion | Nucular 12F | LMX-Motor 60mm | 18s 16Ah LiPo

Post by SlowCo » Nov 10 2019 2:52pm

Nice work!
Get a decent road tire on the front rim (14"?) and you'll have a Supermotard :thumb:

ZERONEST   100 mW

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Re: Chinese Pit Bike Conversion | Nucular 12F | LMX-Motor 60mm | 18s 16Ah LiPo

Post by ZERONEST » Nov 10 2019 4:16pm

great project! thinking of also converting a pit bike myself but running a qs motor 120 70h as it already runs the standard pit bike sprockets to match the rear. also running 18s and 16-20ah, do you have any idea on what range you might get from your pack yet? or too early to say yet?

:thumb: :thumb: :thumb:

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Amaxophobie   1 mW

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Re: Chinese Pit Bike Conversion | Nucular 12F | LMX-Motor 60mm | 18s 16Ah LiPo

Post by Amaxophobie » Nov 11 2019 3:05pm

@SlowCo
Thank you!
Exactly, the front rim is 14" and the back rim is 12". I intend to use it mostly offroad so the plan is to change the back tire to a cross-profile. 200 meters from my apartment there is a big forest with lots of trails and paths. So choosing between road and dirt was not that hard :wink:

@ZERONEST
Thank you!
I thought about that motor too but it would be too overkill for this small bike. Also the size would be a problem. The distance between the two straight arms on my frame is only 220mm wide. With an overall length of 215mm the QS would stick out to one side in order to maintain a straight chainline.
And last but not least the LMX-motor is more capable than one would think. For the size and weight of the bike (55 kg) it is the perfect motor in my opinion. Also the small size makes it look underpowered and I really like understatement 8)

I uploaded a new video to my youtube channel with the nucular 12F installed. Build pics will follow in the next days.

Stunt scooter conversion |AP 80100 | KLS 7218S | 23 kg
viewtopic.php?f=35&t=97391

Youtube
https://www.youtube.com/channel/UCqr3x7 ... 5kRkTCIZng

SlowCo   100 kW

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Re: Chinese Pit Bike Conversion | Nucular 12F | LMX-Motor 60mm | 18s 16Ah LiPo

Post by SlowCo » Nov 11 2019 4:19pm


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