PSA: King Song KS-S22 motor issues, how to identify and fix

[supercurio]

The KS-S22 units, from early production have experienced a few different motor failures, all of them which require attention.

These problems range from annoyance to a significant risk of harm if not addressed, here's what I've learned by talking with multiple owners, dealers and a King Song representative.

List of known issues

Knocking sounds

Severity: minor

Solution: tapping the motor with a mallet (at home) or replacing bearings (dealer service)

https://youtu.be/tARgOXM7Nlg

Note that although this video is made by King Song, the form is not optimal and might cause more issues. Side covers screws should be tightened using a star pattern. A trained mechanic can do a better job.

Examples:

https://www.facebook.com/694652144/videos/5772071279471150/
https://www.facebook.com/1342021424/videos/1114291589433539/

Details:

When this problem occurs, the general understanding is that one or both of the bearings are not fully aligned and seated into the motor side covers. When the motor rotates, the bearing shifts a little bit which makes a sound that's amplified like a speaker by the side cover.

Notes:

The bearing operating under stress will somewhat damage the bearing a little, therefore a bearing replacement or upgrade, while it doesn't seem required in some cases is not an unreasonable solution.

 

Scraping sounds 1

Severity: high / critical

Solution: opening the motor and clean off metallic debris as shown in this KingSong video:

https://youtu.be/-eJUAsWquu0
Note that the form is not perfect either since debris could fall back into the motor if following the exact method demonstrated.

Identification:

Motor makes scraping sounds when rotating. Let us know if you have more details, including how it differs from scraping sound 2.

 

Scraping sounds 2

Severity: critical

Solution: motor replacement

Identification:

The problem will typically manifest with rubbing sounds which can be mistaken with the tire, rocks scraping the mudguard. The symptoms are temporary and easy to dismiss.
You will likely notice that the sound is different when the unicycle is leaning to the left or right, apparent when turning or carving.

After confirming that the sound indeed comes from the motor itself and not a twig hitch-hiking in the wrong spot, the rider should head back home at limited speed and inform the dealer.

At any point later in time, the scraping sound will come back, amplified by power demand when accelerating or slowing down. At this point, it is imperative to stop riding immediately: the motor defect is capable of burning the MOSFET of the mainboard without warning, leading to an inescapable crash, harming the rider and damaging the wheel further.

Associated symptom:

Perceivable motor vibrations and self-balancing tremors at 0 or low rotation speed.

Examples:

2nd phase, riding slowly:
https://youtu.be/hFwHRKY_6Qw
https://www.youtube.com/shorts/cv2GL91zhUI

Demonstrating the problem without riding: unexpectedly burns the mainboard:
https://youtu.be/ZQub66zE_Wc

BTW: it's me and my S22 on these 3 videos

Details:

The exact cause is not understood yet but should once motors exhibiting this fault will be opened and analyzed.
Potential causes are:

1. loose hall sensor
2. loose magnet(s)
3. escalation of scraping sounds 1 due to internal metallic debris

 

Unsealed motor covers

Some of the S22 motors are lacking a seal between the motor covers and the rim. It means that in wet conditions, water and various contaminants could enter the motor, resulting in corrosion. Think: riding on slushy salty roads during winter.

I need more details on that and will update the post accordingly.

 

What about new production?

King Song worked with their motor supplier to fix the issues identified.
A KS rep I talked to in private told me that motor with production date of July 2022 and onwards implement the fixes, which were not specified.
This was confirmed by a Chinese friend who received a replacement motor, which serial number indicated a production date of end of June 2022.

It is unclear if all motors produced present a defect. So far, although the failure rate is trending upwards, it remains below 10%. At the moment I don't believe all motors are affected.

If your motor is affected and the problem requires replacement, I would recommend to request a replacement from July 2022 or newer to reduce the risk of a new occurrence according to KingSong's statement.
Given the current state of things, I don't believe either that sending all wheels back to dealers for a motor swap would be a practical course of action.
However I wanted everybody here to know what's up, because nobody should crash and get hurt due to bad motor, as long as we know how to recognize defects.

Edited August 18, 2022 by supercurio

[supercurio]

How to identify your S22 motor production date.

It's easy, you'll find that info in the serial number, either printed on the motor cover itself or a sticker (that might be gone now) with a QR code
Here's mine.

By the way, please don't share yours unobstructed - it could used to get undue warranty claims (although not now since KS asks for the original motor back)

 

As you can see, my defective S22 motor was produced on the 28th of May 2022.

Edited August 18, 2022 by supercurio

[wstuart]

Wow, nice post!  Thankyou!

[Averytingwong]

Oh hey that's my s22 in the link about the knocking! Great job compiling everything here.  

Malleting the bearings back into alignment seems to have worked for a day, but it came back today, I just did another round of hammering, although I should try the star pattern when tightening the screws as you suggested.

[Fonzerra]

All the joy of a new wheel has been ripped out of me. First 10 months of impatient waiting to get the wheel and now all the problems being reported.

There aren't many fun miles between the fear of a cutout.

I have had zero problems with my S22. No strange noises or other strange things. Like most, I had some screws that needed to be tightened, but otherwise nothing else. It runs like a dream and currently has completed the first 100 km.

My engine was produced 06-06-2022. How long do I have to worry about problems that probably won't come at all?

[onkeldanuel]

The knocking sound of bad bearing alignment should appear after few km (probably first 100km or sooner at offroad) if affekted (Motorcovers tughtening not 100% correkt at factory) and i guess other Motorproblems too at first 100-200km.....

 

Mainboard/bad mosfets i dont know really

 

I had a few KM in right now with my new S22 (motor Produced April) and the only sounds i Noticed are i guess from Fender or loose screw anywhere....

 

its some vibrating / humming noise at accellerating from/at low speed somethimes (but no Motor Revolution associated Clicking/knocking or something like that)

[Rollin-on-1]

2 hours ago, onkeldanuel said:

The knocking sound of bad bearing alignment should appear after few km (probably first 100km or sooner at offroad) if affekted (Motorcovers tughtening not 100% correkt at factory) and i guess other Motorproblems too at first 100-200km.....

 

Mainboard/bad mosfets i dont know really

 

I had a few KM in right now with my new S22 (motor Produced April) and the only sounds i Noticed are i guess from Fender or loose screw anywhere....

 

its some vibrating / humming noise at accellerating from/at low speed somethimes (but no Motor Revolution associated Clicking/knocking or something like that)

The spring on the motor cable can resonate and vibrate under certain conditions.  You can determine if this is the source of your noise by wrapping the spring in athletic tape or applying plasti-dip.  If you continue hearing a noise then it would be a good idea to rule out motor noise as the source.

[JerJer]

With torqued acceleration (i.e uphill) mine was making a strange howling noise that sounded like a disgruntled Wookie, I feared it was motor trouble, but, it turned out to be vibration of the transparent motherboard cover due to slightly loose screws not holding it down firmly enough.

I have heard a scraping sound ( only a few times so far and very briefly ), that I am hoping was caused by an occasional piece of gravel getting briefly lodged in the tyre tread and scraping between the tyre and mudguard and then getting flung out at the other end.

Having hoped this I am still going to check the motor's date of manufacture( thanks 'supercurio' for the info ).

[jrhz06]

Had buzzing noise on hard acceleration. Called my dealer and they requested that I take a video of what I was hearing. Sent them the video and got notified not half an hour later that they were arranging for my wheel to be shipped back to them. Not great news but great reaction and response from my dealer. Hopefully they don’t need to keep my wheel to long before they find and fix the issue. This just started after 100 km of mixed street and trail riding. Checked all screws for tightness and all were good. Suspecting motor issue.

[Dubardo]

Am I the only one with this gridning noise?

 

[jrhz06]

3 minutes ago, Dubardo said:

Am I the only one with this gridning noise?

 

You’re not the only one. That’s what I called the buzzing sound. Mine is the same and it’s on its way back on warranty. Don’t know if it matters but my motor has a build date of 20220311, so it’s an early one.

Edited August 20, 2022 by jrhz06

[Dubardo]

4 minutes ago, jrhz06 said:

You’re not the only one. That’s what I called the buzzing sound. Mine is the same and it’s on its way back on warranty.

That bad?

[jrhz06]

I sent a video of that sound and my dealer suggested returning it under warranty for evaluation by their technician. Once they get it and make a decision on what it is I’ll post their response. For now, don’t know what it is but suspecting it’s motor related. Wheel has never been dropped or ridden in the rain.

[Dubardo]

I sounds more like a vibration caused by the high torque demande on the motor, maybe a loosed parts.

[onkeldanuel]

27 minutes ago, Dubardo said:

I sounds more like a vibration caused by the high torque demande on the motor, maybe a loosed parts.

With my description of vibrating noise a few posts earlier i ment 100% exactly this like in your Video.....

 

i dont think its the Motor , more like something loose , this Sound appears besides hard accelerating , at riding over Grass at lowspeed to sometimes, more like resonating noise 

Now i have Changed the tire...and fastened all screws arround (2 from one side of the motorholder were slightly loose....

Anyways i cant test it before Wednesday

Edited August 20, 2022 by onkeldanuel

[Tawpie]

47 minutes ago, Dubardo said:

Am I the only one with this gridning noise?

 

Look at the early ride videos that (I think it was) e-riders store made… his spring would vibrate under acceleration and braking. You can try turning the spring and its top nut to tighten and/or loosen it a half turn or so. If that fixes it you're in better shape—but even without the *grind it does seem noisier than I'd like. The motor should be basically totally silent, maybe a little bit of grunting depending on how hard you're pushing, but not much more.

[Dubardo]

3 minutes ago, Tawpie said:

Look at the early ride videos that (I think it was) e-riders store made… his spring would vibrate under acceleration and braking. You can try turning the spring and its top nut to tighten and/or loosen it a half turn or so. If that fixes it you're in better shape—but even without the *grind it does seem noisier than I'd like. The motor should be basically totally silent, maybe a little bit of grunting depending on how hard you're pushing, but not much more.

I untorqued the spring to a few turn when unsprung(the wheel in the air) to have maximum load. Haven't tested the noise. Going out right now for further investigation. It doesn't grind when I wheel lift.

[jrhz06]

20 minutes ago, onkeldanuel said:

With my description of vibrating noise a few posts earlier i ment 100% exactly this like in your Video.....

 

i dont think its the Motor , more like something loose , this Sound appears besides hard accelerating , at riding over Grass at lowspeed to sometimes, more like resonating noise 

Now i have Changed the tire...and fastened all screws arround (2 from one side of the motorholder were slightly loose....

Anyways i cant test it before Wednesday

I thought the same as you and did the same. No change in sound.

19 minutes ago, Tawpie said:

Look at the early ride videos that (I think it was) e-riders store made… his spring would vibrate under acceleration and braking. You can try turning the spring and its top nut to tighten and/or loosen it a half turn or so. If that fixes it you're in better shape—but even without the *grind it does seem noisier than I'd like. The motor should be basically totally silent, maybe a little bit of grunting depending on how hard you're pushing, but not much more.

I’m using an air shock so not a loose spring.

[Omikens]

My s22 has been making the same sound since the beginning. It only happens during a specific speed when I accelerate or brake. I have already done 400km on my wheel and zero problems. I think the sound is a fender vibration or other relatively loose parts.

Edited August 20, 2022 by Omikens

[onkeldanuel]

25 minutes ago, jrhz06 said:

I thought the same as you and did the same. No change in sound.

I’m using an air shock so not a loose spring.

You changed the tire too?

[jrhz06]

Yes, put on a Pirelli Angel. I like the tire. Cleaned and made sure all screws were tight. Very frustrating as the wheel rides great except for that sound. At my age I don’t want to take any chances with cut outs. I even tried lowering the ride height to see if that had any effect on it, no change.

Edited August 20, 2022 by jrhz06

[onkeldanuel]

Ok...yeah so i wonder what your dealer finds out then..

[Dubardo]

Still making the grind. But it sounds more like a resonance frequency. If i go over x speed and high torq it doesn't do it. It's at a certain speed. It's windy today so its hard to make test. 

[onkeldanuel]

31 minutes ago, Dubardo said:

Still making the grind. But it sounds more like a resonance frequency. If i go over x speed and high torq it doesn't do it. It's at a certain speed. It's windy today so its hard to make test. 

Yeah its same at mine....

[Dubardo]

A friend told me is is doing the same thing but thought it was normal. And he might be right, that would explain a lot.

It's the over torque protection from KS. That would explain it only sound at lower speed. It would be kinda electric break to prevent accelerating too fast.

He heard that in a review video.

 

So basically it's a normal grind.