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Discussion Starter #1
I bought my Z125 Pro with 80 miles on the clock in late 2017. It stayed completely stock until recently, which would not have made for a very exciting build thread. Recently, I decided it uses way too much gas and I had to do something about it (that was a joke). So I decided to go electric! Since I no longer have any CC's and I only kind of know what I'm doing, I'll call this bike the Z000 Amateur. Here is my 10 step build plan:

Step 0:
Totally stock Z (except the bar end mirrors). This was actually the day I put it on Craigslist, thinking I would sell this bike and use the money toward a different electric motorcycle. Where’s the fun in that?! After only getting contacted by scammers, I decided to take matters into my own hands and modify the Z.



Step 1: Spend a bunch of money on parts
Next step was motor and battery selection. I went with a 72V 70Ah lithium battery (20S20P of 18650 cells), an 8kW QS hub motor, and a Kelly KSL-7275H controller. We could debate the merits and drawbacks of hub motors but this is not a large motorcycle as you know, so I went with something that packages really well and leaves room for batteries.



Step 2: Take out the engine!
The engine and rear wheel are no longer required so I took those out and sold them. I love how easy this bike is to work on and I had the engine out all by myself in only a few hours.
I sold parts on eBay to help recovery some costs of the motor and battery.
If you’re gonna follow this build thread, get used to bad pictures in a dark garage lol. It’s a shared garage for the building and the landlord has the lights come on at night on a timer. That means it is always dark.



Step 3: Mock up battery box
At this point you should have tons of Amazon boxes of all different sizes from the junk you’ve bought to support this project. Cut one up and use it to test fit your battery box.
Now you can see why I went with the hub motor – leaving the entire engine area wide open leaves room for a decent size battery.
I wanted to go with an aluminum battery box. Since I’m not a good welder I plan to trap the battery between two plates separated by spacers, with closeouts around the outsides. I modeled it up in CAD to create a file for cutting the plates.




Step 4: Motor testing!
Unfortunately I didn’t take any great pictures of this setup. Maybe that’s for the best so you don’t have to see how messy my bedroom is. I had the wheel/motor on my rear stand and then a rat’s nest of wires between components. This was to make sure I can get the motor running smoothly and responding to throttle input before I bring it all downstairs to the garage.
Worked through a few issues, but all the hardware appears to be in good shape! There is some shoddy wiring here somewhat attributed to the Chinese battery manufacturer but some my own doing. That will get fixed up once everything gets installed on the bike. For now, it’s good news that I can talked to the motor controller and make it do what I want.



Step 5a: Install fender delete kit
Believe me, this step is super important. It has nothing to do with the electric conversion but the stock fended just looks bad. I can’t believe I left it there so long
Step 5b: (More) disassembly
I still had a bunch of gas guzzling parts on the Z that needed removal. If you thought it looked stripped down before…
I took off the grips (since I’m going to an electric throttle), fuel system, tank, clutch lever and associated hoses and wires. Now we’re at bare bones.
Extra fuel was donated to my Triumph which will happy drink it up this week.
I’m not too sure what to do with the tank. It obviously isn’t required anymore, but I think the bike will look bad without it. Possibly will cut out the bottom and use for storage or keep a charger in there. Open to suggestions from yall.



[TODO] Step 6: Component mockup
Test fit everything to see how it mounts up. This also drives the wire length and routing

[TODO] Step 7: Paint battery box plates (black, ofc) and tidy up wiring off bike
Pretty self-explanatory…

[TODO] Step 8: Component final install and wiring on bike
Now that everything is pretty and fits the way it should, time to install it on the bike.

[TODO] Step 9: Wire up speedometer
This gets a step to itself since I’m not exactly sure how this works yet. Also, the turn signals (and who knows what else) run through the speedometer so I’m not sure how to keep them working with the new electric speedo. Hit me up with ideas!

[TODO] Step 10: Ride!
 

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Nice! I want to get one of the Chinese electrics and swap in an 8kw motor and controller. My thought has always been to use tool batteries like the 40, 60, or 80 volt stuff you can buy. This would give me a quick change option if I take it to a track. the 8kw motor should put it on nearly equal terms with a Grom/Z125.

Charger goes in the tank, it will be lighter than more batteries. But if you need room for another battery, it can certainly go in there too.
 

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+1 There's been chatter about a project like this, cool to see someone diving in. The result should be all sorts of silly fun.

Welcome to the forum!
 

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Discussion Starter #6
Nice! I want to get one of the Chinese electrics and swap in an 8kw motor and controller. My thought has always been to use tool batteries like the 40, 60, or 80 volt stuff you can buy. This would give me a quick change option if I take it to a track. the 8kw motor should put it on nearly equal terms with a Grom/Z125.

Charger goes in the tank, it will be lighter than more batteries. But if you need room for another battery, it can certainly go in there too.
I think 8kW will be a good power level. Also that is a rated (continuous) power capability so I should be able to push closer to 12kW (16 horsepower) for a shorter time. I've read that these motors are seriously underrated, so I think my limiting factor for power will be the battery which has a max continuous draw of 150 amps.

The one reservation I have about keeping the charger in the tank is that it has a cooling fan which runs continuously while charging and I don't think I would have adequate ventilation if it stays in the tank. Unfortunately the tank on the Z does not rotate up from the front, it just pins in place and bolts down in the back. So that makes it harder to store stuff in it unless I add my own hinge.
 

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Discussion Starter #8
I spent some quality time today cursing at inanimate objects, but the end result is positive! I managed to wrestle a tire over the motor/wheel. Unfortunately the valve stem I have doesn't fit so I can't set the bead and add air until the replacement comes in. The tire is slightly larger than stock for the Z but it should fit under the fender still.

 

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Can you get those motors in a 12 inch wheel? The 13 seems really odd!

I'm wondering if this would be a good way to make a custom race bike frame, wouldn't need to fit the frame to the motor which should make it easier to design. This is still one of my goals, I want to make a mini GP bike that really fits adults, so slightly longer frame, etc. I was going to design around something like a TTR125 motor or maybe one of the turnkey engines that you can buy. But an electric would be SO COOL! Especially if I could pop off a bunch of tool batteries after practice/qualifying for the race.

My only concern about hub motors would be the temperature, how much heat will it be pushing into the tire and will it over cook the tire when you are running a race?
 

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Discussion Starter #11
Can you get those motors in a 12 inch wheel? The 13 seems really odd!

I'm wondering if this would be a good way to make a custom race bike frame, wouldn't need to fit the frame to the motor which should make it easier to design. This is still one of my goals, I want to make a mini GP bike that really fits adults, so slightly longer frame, etc. I was going to design around something like a TTR125 motor or maybe one of the turnkey engines that you can buy. But an electric would be SO COOL! Especially if I could pop off a bunch of tool batteries after practice/qualifying for the race.

My only concern about hub motors would be the temperature, how much heat will it be pushing into the tire and will it over cook the tire when you are running a race?
Yeah it is a weird size and limits tire choices too. Unfortunately their 12" wheels only go up to 5kW and I wanted the extra power. Also since it is direct drive the larger tire will get you a little more top speed for the same max motor RPM.

I'm not too sure how much heat to expect in the tire. I'll have to ride it hard and report back. The motor does have a temperature sensor so the controller will monitor and can reduce current above a certain threshold (recommended 100 deg C). The motor rated power is for continuous operation and I wouldn't be able to use 8kW continuously unless I was trying to keep up with highway traffic for extended time so I don't expect issues with street riding.
 

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Discussion Starter #12
I got everything arranged on the bike this weekend to see how it all fits. Overall I like how it looks!

The battery fits in there well and doesn't really look all that out of place. The controller is a really tight fit on top of it but I think it works there. Right now I don't have it mounted firmly but I can make a bracket to tie into those bolt holes on the side of the frame. I need to relocate the horn too so that will have to attach to this custom bracket as well. I'm not sure if the fairings fit over this yet but I've got my fingers crossed.



The wheel/motor will sit slightly behind where the stock one was. I'm making a plug that goes into the back of the swingarm and provides the slotted mount to hold the motor axle. The cable bundle from the motor runs up along the inside of the chain guard toward the controller.



Once I took the battery and ECU out, the DC-DC converter (72V battery step down to 12V to run lights and gauges) and the main contactor fit in there. Honestly I don't think I need a particularly sturdy mount for these, some zip ties or heavy rubber bands will probably work.



Next step is to pull the battery box back out and cut the spacers that will make sure it holds in this position where I like it. Then I'll get it and the other components mounted permanently and start to finalize the wiring.
 

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Looks like your using and made a mount for the VDS ?
With No ECU, are you using it for another function of some kind
Just love the MacGyver stuff ;)

Nothing but mad respect from me for someone with a passion to mod things so much there willing to do it in a parking garage :wink2:
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And just because you didnt post in the "New Members Introduction" thread, dont think for one minute your getting by me without a welcome Logo :grin2:
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Welcome to the forum ;)
.
 

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Discussion Starter #15
I love the logo! I'm keeping it!

Yeah I don't actually have anything mounted firmly yet in those picture but that is the plan. I didn't make a whole lot of progress lately but hopefully will have time to get everything fixed permanently next weekend. Regarding the stock ECU, I can't think of any reason why I'd still need it. The engine is gone and I'm getting rid of the stock gauges too so there doesn't seem to be anything for the ECU to control.

Today I did get the battery box fixed up and installed for good. I painted everything black, then added a strip of black plastic around the battery. This looks a lot better than bare aluminum and the blue battery plus I think the plastic will help protect against small rocks and debris kicked up by the front tire.

 

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I'm back! It's been a while since I typed up an update, but that doesn't mean I haven't been working.

Things were getting a little tight with the new components so I also freed up some space by getting rid of the unnecessary wiring. There are a whole lot of wires once I cut the harness open and I really gave those Harbor Freight wire cutters a good workout. I even got a little too snip-happy and cut off the horn (oops). The only thing I really wanted to keep was the lighting circuit. However, it turns out everything runs through the speedometer so once I got rid of that I needed a separate standalone flasher relay. It works now and I reduced the the wiring by a lot.



I have a few more components permanently mounted to the Z000 now too. I figured out some brackets once I had everything mocked up and I made them over the last two weekends. I don't have a lot in the way of tools and workshop space so everything takes longer than it should.


The controller packages tightly right above the battery and picks up the old airbox mounts. There is barely any space with steering at full lock, but it does it.


The DC-DC converter goes under the seat, where the battery used to be. This steps the 72V supply down to 12V to run the lighting circuit or any accessories.


I also got the wheel/motor installed! The bike looks super clean from the right side. I'm just hoping I can package everything tightly enough to make it look good from the other side too. You can see the electric throttle is installed too and the original mirrors.



I really think I'm in the home stretch now, but there is still a decent amount of work to go. I have to get the new speedometer mounted and then I have a lot of wiring to do. I'm also planning to have no mechanical rear brake and use the pedal for regenerative braking, but that's for another post. Can't wait to ride this thing!
 

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Discussion Starter #18
Hope everyone had a great 4th!

Between cookouts and fireworks, I managed to get the high voltage wiring trimmed and connected in final configuration (as opposed to the jumper cable mess from the video in the above post). I also worked through the low voltage circuit to get the lights and speedometer working. Everything seems great right now, but I might have to re-calibrate the speedometer once I actually get riding. There is a lot more going on now and the wiring is about as busy as it was with the old engine. Everything will have to get stuffed into a bundle and taped against the frame rail.


I also mounted, but haven't wired in, the rear brake. Like I mentioned, I'm ditching the mechanical brake in favor of regen only for the rear wheel. I figure emergency stops pretty much all come from the front tire anyway, especially with a wheelbase this short. The motor controller accepts a 0-5V signal to control regen so I am getting this signal with a load cell. I mounted the load cell using a custom bracket off the rear brake master cylinder tab and the other end goes to the brake pedal. Since I think a fully rigid brake pedal would feel weird, I used rubber bushings in the mounting holes so there is a tiny bit of compliance like a real brake pedal. The output from the load cell will run through an amplifier to get the 0-5V signal for the motor controller.


I have a small punchlist of miscellaneous items to work on, then will bundle up the wiring neatly against the frame before reattaching the plastics.
 

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Discussion Starter #19
I cleaned up the wiring today and (finally) managed to bead the tire with the help of a ratchet strap. Then I went for a real quick ride just up and down the block! Wow, this thing is fun.

...details and more pictures coming soon. There's still work to do but for now I'm just sitting here with a stupid grin on my face.

Kind of hard to tell in the photo but the wiring is pretty tight against the frame now and I think the fairings will cover it. I might actually leave the plastics off for a little bit just in case any rework pops up on the first few rides and so I can check if anything is getting excessively hot or shaken loose.

 
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