Fellow AK550 Owners Question - Noticeable vibration at deceleration

[jermwars]

If it is like other Kymco scooters - relax- you have 2 years on the drive-train warranty.

Stig

Thats kind of where im at with it...if it causes a breakdown within the 2 year window, then im good...and if it doesnt cause a breakdown by the time 2 years are up, its probably not going to.

Especially since i do about 700 miles a week with it.

(doordash)

[jermwars]

We never did hear a word back from the guy that started this thread, did we...

 

[Neil955i]

Nope. Not yet...

[NomadCF]

I *may* have found your vibration/thump. I just got done swapping my rollers out for 15g sliders. And I was able to create what think is the effect your talking about.

With everything apart I tried creating this issue and I was able to under the following conditions.
1) rollers or sliders werent seated right.
2) the variator bolt wasn't torqued enough. This one's a hard one is the spec is so open about how much to torque the bolt.
3) a variation on #1

Basically what I could recreate was the variator would break loose or snap out de-accelerating under 2800-4200 rpms. It appears the belt applies to much press and there isn't enough resistance from the variator to slowly move back out to it's at rest location and it just jump out alittle.

Also that video about replacing the variator on the AK is F'ing awful! Not only does It just plainly leave out a bunch of stuff, a glasses over all the small stuff as well! I wouldn't even call it a reference at this point. It was enough to show you all the large pieces and play.... But it's all the small stuff that really is what matters!!!

[Stig / Major Tom]

I *may* have found your vibration/thump. I just got done swapping my rollers out for 15g sliders. And I was able to create what think is the effect your talking about.

With everything apart I tried creating this issue and I was able to under the following conditions.
1) rollers or sliders werent seated right.
2) the variator bolt wasn't torqued enough. This one's a hard one is the spec is so open about how much to torque the bolt.
3) a variation on #1

Basically what I could recreate was the variator would break loose or snap out de-accelerating under 2800-4200 rpms. It appears the belt applies to much press and there isn't enough resistance from the variator to slowly move back out to it's at rest location and it just jump out alittle.

Also that video about replacing the variator on the AK is F'ing awful! Not only does It just plainly leave out a bunch of stuff, a glasses over all the small stuff as well! I wouldn't even call it a reference at this point. It was enough to show you all the large pieces and play.... But it's all the small stuff that really is what matters!!!

I'm certainly no mechanical expert, and only toss these thoughts out there with that much weight behind them....

I think roller weights 'cannot' be miss-seated from the factory - unless they have now worn so far (thousands of miles of riding)  that they have shrunken in their seats. A miss- seated weight would prevent the parts from closing properly - and would cause severe issues and be quickly noted on the first ride. (new scooters do not come with Dr P slide weights)
And as for a variator nut not reaching the proper torque: the torque figure is supplied to insure that it does not come loose (or is so massively over-torqued that it destroys something) I'm thinking it is either loose, and finger tight flopping, or tight enough to secure the parts. I don't see that there is any in-between: it is either loose, or it is not....and again it would show itself very, very soon ---within a mile down the road.

I offer these counter-remarks because I think we might be unnecessarily alarming the fellow who is hearing/feeling something on his 550. I for one - do not think there is a mechanical fault at work in his scooter.

Stig

[NomadCF]

I'm certainly no mechanical expert, and only toss these thoughts out there with that much weight behind them....

I think roller weights 'cannot' be miss-seated from the factory - unless they have now worn so far (thousands of miles of riding)  that they have shrunken in their seats. A miss- seated weight would prevent the parts from closing properly - and would cause severe issues and be quickly noted on the first ride. (new scooters do not come with Dr P slide weights)
And as for a variator nut not reaching the proper torque: the torque figure is supplied to insure that it does not come loose (or is so massively over-torqued that it destroys something) I'm thinking it is either loose, and finger tight flopping, or tight enough to secure the parts. I don't see that there is any in-between: it is either loose, or it is not....and again it would show itself very, very soon ---within a mile down the road.

I offer these counter-remarks because I think we might be unnecessarily alarming the fellow who is hearing/feeling something on his 550. I for one - do not think there is a mechanical fault at work in his scooter.

Stig

And you very well would be right. But the fact remains that if I used the lower end of the torque spec I got a thump on decel. And just because some comes from a factory doesn't mean it's perfect. That variator cover could be just slightly cockeyed or sticking on one side. Which what result in a weight offset issue.

And again, as I've said on a few of these threads; mine doesn't have this thump or vibration on decel. And I could only create one by creating these two issues. Take it for what it's worth or not.

[Neil955i]

Wouldn’t be the first time the factory had omitted to correctly torque up a variator nut... The cause of my warranty claim at <700 miles!

[jermwars]

I *may* have found your vibration/thump. I just got done swapping my rollers out for 15g sliders. And I was able to create what think is the effect your talking about.

With everything apart I tried creating this issue and I was able to under the following conditions.
1) rollers or sliders werent seated right.
2) the variator bolt wasn't torqued enough. This one's a hard one is the spec is so open about how much to torque the bolt.
3) a variation on #1

Basically what I could recreate was the variator would break loose or snap out de-accelerating under 2800-4200 rpms. It appears the belt applies to much press and there isn't enough resistance from the variator to slowly move back out to it's at rest location and it just jump out alittle.

Is that right!! Interesting...most interesting...

Thank you for the help by the way! Immensely appreciated.

The only thing that comes to mind as i mull that over is that it DOESNT do it, under any load or RPM unless i get it up to about 40 mph...that makes me think it has something to do with the secondary pully (driven pully) returning to its fully open state because i think that one doesnt start to close until you get moving a bit...I THINK...I had it in my head that the variator end closes up first off.

I might have that all backward...i do that a lot

Another thing is that if i brake real hard i cant feel it NEARLY as much...more of a little "pop" is all

But if i let the engine slow it down and dont use the brakes as much it becomes a bit of a "bang"

Happens right at 23mph either way

Approaching 1500 miles and it doesnt seem to be getting any better OR any worse...Which is kind of annoying on its own!

[jermwars]

I just wish id bought it off Amazon

Send it back for a new one

[Ruffus]

@jermwars, I do not have a AK 550, and it's a pity to have such an issue on a brandnew bike.
I would try a little bit shorter drivebelt than the mounted one. Could be completely wrong, but if it would bother me that much I would risk this $$ just for the point.

[jermwars]

@jermwars, I do not have a AK 550, and it's a pity to have such an issue on a brandnew bike.

That part is what really gets me...And the fact that its not an isolated issue.

I didnt even start this thread! I just have the EXACT same issue that WEL does.

Exactly the same as what he described.

I think he forgot he started the thread because i havent heard back from him and its been a couple weeks now

[rjs987]

ON any CVT both pulleys have to change at exactly the same time if it is running right. There is no delay with either pulley changing "after" the other but both change at the same time. The only case where that is even possible is if the wrong belt that is too long and doesn't belong on this CVT at all is installed. In that case nothing will work right from the start and you would get NO movement to the rear wheel or even the clutch since a wrong belt like that would simply spin or slip on the pulleys and not grab at any speed.

[jermwars]

ON any CVT both pulleys have to change at exactly the same time if it is running right. There is no delay with either pulley changing "after" the other but both change at the same time. The only case where that is even possible is if the wrong belt that is too long and doesn't belong on this CVT at all is installed. In that case nothing will work right from the start and you would get NO movement to the rear wheel or even the clutch since a wrong belt like that would simply spin or slip on the pulleys and not grab at any speed.

right, right...that makes sense...otherwise the belt would have to change sizes

that should have dawned on me

[mousejunks]

I have 24,000km on my DT350 and the thump on deceleration is mostly gone. It could have been the belt change at 20,000km or transmission components have finally broken in.

[jermwars]

I have 24,000km on my DT350 and the thump on deceleration is mostly gone. It could have been the belt change at 20,000km or transmission components have finally broken in.

man, id just LOVE for it to simply go away...im sooo close to tearing into it but I JUST DONT WANT TO tear into a brand new bike...with a full/valid warranty