[aokjaer]

I have a resonance problem with my AT 2017.
When steady rolling at 40 to 60 km/h in 3 or 4 gear i feel a clear resonance from the engine. It feels like the shaft for the small cogwheel is a little out of true.
The vibrations stops when I pull the clutch and let it roll, hence it is not some kind of balancing of the wheels.

Have anyone seen something similar?

 

[DoubleThumper]

Drive chain too taut?

Welcome to the Forum @aokjaer. Hopefully your symptom is easy to diagnose. There are many intelligent Forum members who often think up brilliant responses.

Feel free to introduce yourself at the New Member Introductions area of the Forum.

 

[BumpyRider]

Possible crash bars or engine bash guard vibrating?

 

[rustynut2]

How many miles on the chain?

 

[aokjaer]

Thanks for the answers, The chain has been changes, because of this problem, so it is new.
It has only done 16000km so it is quite new.
The resonance is not a steady sound like when you have a unbalanced wheel, but more going up and down in a rather slow speed.
I would guess some unbalance in the engine or maybe some misfire from the ignition.
But I don't know, so please advise if you have any ideas.

 

[rider_marc]

Jack up the key and push another AT under it! jk


I'm with the tight chain crowd. Mine is run what might be considered loose, but not sloppy loose.

 

[ORVdaveVA]

I think I have experienced what your talking about. At mid to upper mid rpms when just kind of cruising along and running a lower gear to bring the rpms up just a little. Giving a little throttle, holding steady, like your getting ready to do a roll on acceleeration. The motor gets buzzy and vibrates. I have adjusted to it and can avoid it. Its not a good feeling.

 

[aokjaer]

I have tried to run with a very slag chain but it is still the same.
But I have done some investigation with a vibration app on my phone sitting on the dashboard.
That is interesting since the frequency correspond directly to the drive shaft, so if this is out of true then the problems starts. see the attached screenshot.
The large spike is the repeating frequency, the overall curve is just a slight variation in speed.
I tried to measure the true of the drive shaft with a clock, but it is very difficult since it is a spline shaft, but it indicated a runout of 0,2 mm in one turn.

Have any of you seen a out of true drive shaft before?
I think it must be a manufacturing fault.

 

[rustynut2]

So does the frequency increase with the speed, it should. It should start off slow with first gear and increase as you go through the gears. You could remove the chain and verify its not a wheel/tire problem.

 

[ORVdaveVA]

I think it must be a manufacturing fault.

Thats how I feel too. The tolerances are a little loose in there somewhere.

On or off throttle is fine, but when you let it be its own spinning assembly with no load at certain RPMs it starts the vibes. Feels more inside the motor than the chain slack to me. Probably just happens only on my bike.

 

[DoubleThumper]

I have tried to run with a very slag chain but it is still the same.
But I have done some investigation with a vibration app on my phone sitting on the dashboard.
That is interesting since the frequency correspond directly to the drive shaft, so if this is out of true then the problems starts. see the attached screenshot.
The large spike is the repeating frequency, the overall curve is just a slight variation in speed.
I tried to measure the true of the drive shaft with a clock, but it is very difficult since it is a spline shaft, but it indicated a runout of 0,2 mm in one turn.

Have any of you seen a out of true drive shaft before?
I think it must be a manufacturing fault.
View attachment 72362

Resourceful use of the mobile phone.