AK550 CVT (?) Squeaking Noise

[nokster]

Hi All,

Have been lurking in here since I bought my second hand 2022 AK550 with 8k miles on it a few months back. I'm experiencing an issue and hoping someone with some experience can help.

I have been loving it as a more practical alternative to my other bikes, so I'm a bit upset that I'm afraid to ride it now. It started making an odd squeaking noise this past Saturday after a few hours of continuous riding. It was precipitated by what felt like gears skipping teeth under a hard acceleration from low speed. The same has happened twice before without any consequences. The noise is present only when throttle is applied - no noise at idle, decel. Frequency matches the engine RPM.

Here's a video of the noise:


Anyone experienced anything similar? Assuming this is something in the CVT. I'm used to wrenching on my bikes, but have zero experience with CVTs, so not sure what is going on in there that could create such symptoms.

[Ruffus]

@nokster welcome here!
Do not have an AK550,
@Randyo (pls see link) did have lately not the same but a similar issue, maybe there is some mesh.....

https://www.kymcoforum.com/index.php?topic=33815.msg237200#msg237200

[randyo]

@nokster welcome here!
Do not have an AK550,
@Randyo (pls see link) did have lately not the same but a similar issue, maybe there is some mesh.....

https://www.kymcoforum.com/index.php?topic=33815.msg237200#msg237200

my noise is barely audible and only under a steady cruise at moderate speeds, just giving enuf throttle to maintain speed, nothing out of ordinary with hard acceleration or during deceleration

sounds different than nokster's description

[rjs987]

The entire while listening to that and reading that it feels like it skips once in a while keeps making me think final drive belt (NOT CVT belt).

Make a through check of all the teeth on the final drive belt. You can do this by removing only the bottom outer shell of the belt cover (2 bolts) and then spin the rear wheel while on the center stand. Inspect for any missing or chipped teeth on both the belt and the rear sprocket. If you can inspect the front sprocket as well but you may need a flash light to see that one clearly.
The belt should be sitting somewhat centered on the sprocket but may move side to side. Mine moves but is always at least 1 mm from either side of the rear sprocket. That's the required tolerance. If the belt sits tight to one side or the other it can squeak.

I've not heard that sound at all on mine. I did document how to adjust the belt tension some time ago. I also removed and replaced the CVT belt last month and posted about that with some detail.

[nokster]

The entire while listening to that and reading that it feels like it skips once in a while keeps making me think final drive belt (NOT CVT belt).

Make a through check of all the teeth on the final drive belt. You can do this by removing only the bottom outer shell of the belt cover (2 bolts) and then spin the rear wheel while on the center stand. Inspect for any missing or chipped teeth on both the belt and the rear sprocket. If you can inspect the front sprocket as well but you may need a flash light to see that one clearly.
The belt should be sitting somewhat centered on the sprocket but may move side to side. Mine moves but is always at least 1 mm from either side of the rear sprocket. That's the required tolerance. If the belt sits tight to one side or the other it can squeak.

I've not heard that sound at all on mine. I did document how to adjust the belt tension some time ago. I also removed and replaced the CVT belt last month and posted about that with some detail.

Thanks, I'll definitely check the belt and sprocket first.

FWIW I put it up on the center stand today and found that the noise is only generated while the rear wheel is loaded. When its freely spinning, there is no noise. When I'd apply enough rear brake to slow the wheel with the throttle, the squeak becomes apparent.

[rjs987]

Search for and read my post in this sub forum on adjusting tension on the final drive belt. There is a good YouTube video from another member that shows a lot of what I have provided in print here. In that video the member mentions about making a hole in the bottom inner belt cover to slide the adjuster tool into without the belt holder attached. I made a slot in mine so I can keep the belt holder bracket attached. There are enough gaps and holes already in the covers for the belt that one small hole won't make a difference and most of it is covered anyway when the bottom cover is replaced.

[nokster]

Documenting this saga here:

I've got a new hypothesis as to the source of the noise. While cleaning and inspecting the belt and final drive, I took off the small 3-bolt cover at the transmission output sprocket, behind which there is a bearing. Looks like the seal on the cover isn't holding, because some rust is present along the bearing's bottom edge. Listening again to the noise, I noticed that the squeaking noise is not matched to engine RPM, but wheel RPM, and only present under throttle - and it only happens after a bit of riding, so things have warmed up. Thinking that throttle application could load that bearing causing it to generate noise if its fouled inside!

Dealer service appointment Thursday, we'll see if they concur.

[rjs987]

Sounds like that could be it then. Not great fun replacing that bearing, though I haven't attempted anything there. Until you take care of that or determine that it might be something else maybe get some ACF-50 to put on that rust and get rid of it. I've been using ACF-50 on the exhaust parts on mine and have very little to no rust where I would expect a lot to be for riding all year in cold snowy weather. Before I bought that stuff I did notice some rust starting on the muffler bolts and pipes and clamps but the ACF-50 almost eliminated it and regular use keeps it away. Same stuff used on military aircraft for anti-corrosion. Careful if you spray it (spray can) as it can get all over. Best to put some in a small cup or the cap and use a brush to apply or spray directly on a rag and wipe it on. Those are the ways I put it on. The rag method allows me to get it coated all the way around the exhaust pipes and clamps back behind where I cannot get my hands or fingers. Available on Amazon.