LMX 56 Loud knocking sound with engine

[Micro-Tech]

Hello,
I'm writing regarding a problem with my LMX56. The problem started about two months after I bought it. However, after contacting LMX, I was pleasantly surprised and informed them that a new motor would be shipped.

The problem is a rather loud knocking sound (not a humming sound) coming from the motor. After replacing it with a new one, the knocking persisted. It didn't happen for a while after the replacement. It occurs regardless of whether I'm riding the throttle or pedaling. Sometimes the knocking is quiet, sometimes loud. I've attached a link to a video with the recording.
After contacting LMX again, I was told to check the bolts' tightness. I don't know how tight they should be, but I'm quite an experienced user, and the tightening isn't very tight, but rather gentle. There's definitely no play that would cause the knocking.

Maybe someone else has had similar problems.

 

[Blake2020]

So after service support is great?
I’m Australian and the 64 is on my shortlist.

 

[geofft]

The problem is a rather loud knocking sound (not a humming sound) coming from the motor. After replacing it with a new one, the knocking persisted.

Just wondering if this could be chain skipping on the sprocket teeth, most likely on the rear sprocket I guess. I suspect this may feel like it's coming from the motor, might be worth getting someone with a good eye to ride alongside you and see if they can spot anything amiss.

 

[Micro-Tech]

I'd say skipping on the sprocket. That's knocking from the engine.
I checked the bolts for tightness, and everything's fine. As you can hear in the video, there's no rule for when the knocking starts. But if it starts, it knocks constantly. And whether I press hard on the pedals or lightly, or gently on the throttle – it doesn't matter. The knocking is there. I've also changed the power and assist settings in the app.

PS. Regarding service... hmm, sometimes the replies are slow. I was immediately pleasantly surprised by the engine replacement, but when the new engine started knocking after two weeks, I was devastated

 

[DanGT86]

does it knock without the chain if you just rev the motor through its range?

 

[Micro-Tech]

It only knocks under load. I forgot to add. If I lift the rear wheel, the knocking stops.

 

[DanGT86]

The motors on the lmx have been tricky for me to drive with some controllers. It has something to do with the hall sensor placement making them very susceptible to electrical noise.

The weird thing is that it is across 2 motors and why all of a sudden? Seems like if they had the controller tune correct then this wouldn't just show up now. Maybe your motor hall sensor wiring has a bad connection and its losing synch with the controller.

Can you run it on a test stand or rollers and provide some load while you look for mechanical issues like a chain not meshing with the sprocket correctly? Maybe it's a tensioner bearing?

If you completely rule out mechanical issues you should go through the motor wiring carefully. Look for loose or contaminated connectors.

Does the controller log errors in some way that might clue you into a possible cause?

 

[Micro-Tech]

I checked the chainrings and nothing is skipping. The tension is correct. I've cranked the engine as much as I could (I didn't split it) and checked the connections. I've also focused my suspicions on the alignment because it seems to me that it's not the mechanical fault per se, but the controller or something related. It's a shame there's no software for connecting it (like I have in the LMX 64 . I'm very disappointed. A bike at this price shouldn't behave like this, especially since it's a more expensive version. And the new engine has the same problem. I haven't even ridden it 800km
As for the rollers, I'm planning to get some rollers for a test drive.

I'm from Poland, and shipping a bike to France is a bit scary. So I'm trying something myself.