QS 138 70H with Gearbox

[dforesi]

I was browsing some Youtube videos on saw this motor mentioned on a couple channels but I can't find too much information on it:

https://www.aliexpress.com/item/1005001 ... Uad7bRfvkQ





I'm planning out a conversion for a full size motocross bike and thought this could be ideal. The 90H motor seems like it would be better from a power perspective but having something like this would eliminate the need for any type of jackshaft. This could be a nearly bolt in solution as the sprocket location would be ideal as well.

Thoughts?

[john61ct]

interesting, want to see the torque curve on that compared to the vanilla one

[dforesi]

It's posted in the Ali link

Gearbox motor:


regular 70h

[dforesi]

Looks like you would have to plot some points on excel for both and compare apples to apples. Clearly they are measuring at the shaft in both cases, and the gear box motor has a 2.35 reduction so it makes these two graphs hard to compare.

[hugok]

I have ordered one but I'm still waiting for it to be shipped since there was a lot of backorders after chinese new year.

[dforesi]

Well please keep us updated!

[Jordan325ic]

I have one of these on my bench right now. Haven't hooked it up. My only complaint is that transmission fluid leaked out everywhere during shipping. I'll take photos when I take off the transmission cover plate to fix this.

[dforesi]

From the photos I saw, it looks like there is a pressure release nipple on the case that's held on with a zip tie. I imagine that its not fluid tight. Perhaps that is where it evacuated from?

What do you plan to use it for?

[Jordan325ic]

From the photos I saw, it looks like there is a pressure release nipple on the case that's held on with a zip tie. I imagine that its not fluid tight. Perhaps that is where it evacuated from?

What do you plan to use it for?

That was my first thought, but on cursory inspection it appears to be leaking from the gasket/seal face. But I haven't had a chance to investigate.

It will go into a 1974 yamaha dt250.

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[Elektrosherpa]

Now that's "MY KIND" of bike.
Looking forward to see how you'll do it

[markz]

I'd like to know the gear reduction, and whats the deal with the keyway on the shaft?

[j bjork]

I have one of these on my bench right now. Haven't hooked it up. My only complaint is that transmission fluid leaked out everywhere during shipping. I'll take photos when I take off the transmission cover plate to fix this.

Then you can take the opportunity to photo and measure the gears
I havent seen any info about if it is spur or helical gears, or how wide they are.
Maybe I have seen tooth count somewhere, but I am not sure.

[SlowCo]

I'd like to know the gear reduction, and whats the deal with the keyway on the shaft?

Then use the link in the first post...

[dforesi]

From the photos I saw, it looks like there is a pressure release nipple on the case that's held on with a zip tie. I imagine that its not fluid tight. Perhaps that is where it evacuated from?

What do you plan to use it for?

That was my first thought, but on cursory inspection it appears to be leaking from the gasket/seal face. But I haven't had a chance to investigate.

It will go into a 1974 yamaha dt250.
20210213_165239.jpg

Jordan, great project. Where did you order your motor from? I am trying to get one shipped to USA. How long did it take and what did you pay?

[jhoexp]

Then you can take the opportunity to photo and measure the gears
I havent seen any info about if it is spur or helical gears, or how wide they are.
Maybe I have seen tooth count somewhere, but I am not sure.

Hi, my first "real" post here... so I hope I'm off to a good start.
I have got this motor for a few weeks but started working on it just now.

Having seen how bad usually are these chinese manufacturer of cheap electric motors, this looks decent quality. Anyway they (QS Motors/SIA Ecosys) still looks amateurish at best in eveything else: datasheet, performance graphs, pr/marketing, etc....
Anyway in my case they removed the oil before shipping, mine has just a few ml left inside.

The gear reduction looks fine, it's 45/19 (2.36:1) helical gears. The output gear is almost 12mm thick.
The output shaft is 18mm on the inner side and 20mm on the outer. Bearings on the output shaft are 6203 and 6004 made by C&U. They look decent, but it's an easy upgrade if needed....
I have roughly checked hardness of the output gear, comparing to what I know, and it looks like 55/60 hrc.

The venting "thing" looks pretty well tought, even if they sealed just the inner perimeter and not the whole cover.

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As you can probably see I had to face/modify/cut the motor mounts, because they are just useless (unless you have a pitbike, I understand).

This may be my first post but I have been lurking in the dark and following your posts, that were/are a very good source of inspiration! Looking forward to see your build with the YZF, I am doing an Husqvarna TE 250, but given how lazy I am and all the latest valid excuses (work, covid, etc..) it will probably be done for the late summer.

I also agree with you about what you expressed in other posts, how poor the situation is now regarding controllers: we have motors but the few good escs are way to expensive/big and not really suited for the use we plan. Let's hope something changes soon.

[SlowCo]

I also agree with you about what you expressed in other posts, how poor the situation is now regarding controllers: we have motors but the few good escs are way to expensive/big and not really suited for the use we plan. Let's hope something changes soon.

Thanks for posting the photo's of the gear reduction
It looks well designed and strong enough for most use cases. Regarding the controllers: what's wrong with the controller options they (QS Motors/SIA Ecosys) offer to go with this motor? The EM150-2SP or EM200SP seem to be more then capable of powering this motor.

[jhoexp]

Regarding the controllers: what's wrong with the controller options they (QS Motors/SIA Ecosys) offer to go with this motor? The EM150-2SP or EM200SP seem to be more then capable of powering this motor.

They are low voltage (72V) basic escs. They are sure good enough for now, but already serioulsy hindering max motor power, rpm and overall efficiency. A much higher voltage controller will open new levels of performance at higher efficiency, positively affecting the whole bike use, not only power but also weight, efficiency, fast charging, etc... It makes no sense pulling 400A at 72V @low rpm, when you can have the same power with a much broader rpm range and way less heat pulling 200A @144V or even better 100A @288V.
Alta, KTM, etc... they all have chosen much more higher voltage system with smaller motors and gear reduction.

This low voltage system are ok and safer for DIY, but acceptable just now that electric bikes are a novelty and the whole market is still in it's infancy. We need high voltage to have all the power and efficiency of oem bikes.

[j bjork]

First time I have seen how the gear reduction looks, thanks

It is nice that they put a support bearing on the outside of the motor axle.
It will be interesting to see how it holds up when someone starts to push it.

I think the BESC G4 would be really interesting to try on these motors.
700 phase amps, and was it max 130V?

[john61ct]

As you can probably see I had to face/modify/cut the motor mounts, because they are just useless (unless you have a pitbike, I understand).

I had never heard of that term.

From wiki:

Now the most common style of pit bike (and specifically marketed as Pit Bikes, opposed to introductory Motocross models) A broad look these machines are based on the Honda CRF50 and feature the perimeter frame chassis. New versions feature a CRF 50 motor mounts and may have a displacement between 50-190 CC. The typical wheel size is a 14" front and 12" rear wheel. These models were less expensive (up to 60% less than Honda and Yamaha manufacturers) and use parts compatible with the established aftermarket industry

Rather than messing with custom mounts, would it make sense to buy a suitable frame that already fits the motor

as a starting point for a custom build?

[HrKlev]

Thanks for posting the pictures, Jhoexp!

I am curious if the output shaft is the same size as the non-geared qs 138 motor? Have you checked yet?

[jhoexp]

It will be interesting to see how it holds up when someone starts to push it.

I'll try my best , but I doubt I will have it ready soon...

I think the BESC G4 would be really interesting to try on these motors.
700 phase amps, and was it max 130V?

Yes, and there is also the HESC from Hackey, and the Power velocity 24fets, all VESC derived. But none is really available yet...
Then there is the Kelly KLS-8080 that have 144V versions. Not really cheap and can't really find even one single use case.
I'd like to try, but 800-1000 euros for a jump in the dark...

[jhoexp]

Thanks for posting the pictures, Jhoexp!

I am curious if the output shaft is the same size as the non-geared qs 138 motor? Have you checked yet?

No, unfortunatly it is not. It's a 17mm shaft, the same that pit bikes usually have. I haven't been able to find 520 pinions, in fact I bought a 428 with a new chain and rear sprocket. I hope it holds...

Edit: I maybe wrong, not sure what the non-geared QS 138 has, but the one I have seen was keyed and intended to be used with a belt pulley.

[jhoexp]

I had never heard of that term.

They are pretty common here in Italy, they were originally intended to move around in the pit areas, but now some even race them on mx or kart track as minimotard.

Rather than messing with custom mounts, would it make sense to buy a suitable frame that already fits the motor
as a starting point for a custom build?

Sure, but you will be stuck with a pit bike: it's fun, but really small and useless outside the track.
I want a full size dirt bike and that motor should be capable of powering one. The original QS138 (with no reduction built in) had much friendly motor mounts. I had already designed my whole build around that, but making a good jackshaft is no simple thing... so when this came out I knew I had to make some modifications.

[Jordan325ic]

The gear reduction looks fine, it's 45/19 (2.36:1) helical gears. The output gear is almost 12mm thick.
The output shaft is 18mm on the inner side and 20mm on the outer. Bearings on the output shaft are 6203 and 6004 made by C&U. They look decent, but it's an easy upgrade if needed....

Just curious, where are you measuring the output shaft dimensions? My output shaft matches the pdf, 17mm/14mm
Edit: Nevermind! I missed that you mentioned this a few posts up.

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QSMOTOR Z138-03 Mid Drive Motor with gearbox.pdf

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[Jordan325ic]

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So as I understand it the correct orientation is:
#1 - vent, ideally facing downward.
#2 - Drain plug, ideally the lowest point of the fluid housing.
#3 - Fill plug.

I wonder how sensitive the unit is to other mounting orientations, besides the increased difficulty in draining and re-filling the unit...