Kymco xciting 250 noise under acceleration

[ZEN]

Xciting 250 2008 year when accelerating I'm getting a vibration sound from the drive belt area. My People 150 is totally quiet under the same condition. Dealer said this was normal noise on the 250, I had them replace the drive belt at 6900 miles along with new oem rollers, but still have same vibration sound. Could it be belt vibrating since it is longer than the 150 belt? Quits totally when at level cruise speed.

[Hoolander2]

It doesn't sound normal to me.  I have an Xciting 500 which doesn't do that.  I couldn't really say what would cause it. 

[ts1]

What makes noise, wears out.

The belts have different length, thickness and wedge profile, as every variomatic is different.
Perhaps it is possible to run the engine on the center stand with open vario cover (if the cover has no counter bearing) and take a look.

What did the old belt and rollers look like? This would give an strong indication!
I have the x500 and changed first time at 25000km (6900 miles isn't much for the Xcitings build quality). They just rubbed down below their safe tolerances, no unusual wear.

[ZEN]

Service tech said old belt had very little wear and was still within oem specs. The rollers had just started to show flat spots but again the tech said they were still in good condition, obviously I had both replaced since I was going to have to pay for the labor anyway. I kind of feel the belt vibrates under load kind of like a stretched belt would do, but  since it has a new oem belt and the set up doesn't have a tension setting or idler system I'm at a loss as to how to correct it. You guys have the 500cc model and it could be that the higher torque that engine applies to the belt system may prevent it from vibrating. Just a thought. Tech also said normal replacement for the 250cc belt is around 12000 miles.

[Hoolander2]

When I put a new belt on my 500 a few weeks ago I used a Gates belt, not an OEM.  I left out the washer which is in the 500 variator just for an experiment.  That had the effect of putting more tension on the belt.  I did notice significant vibration and noticed the belt jumping and slapping the cover when I ran it on the center stand with cover off -- especially when reving up a little. That diminished after a few minutes of running.  After a few miles of riding that way, I decided to put the washer back in to relieve the tension which got things pretty much back to normal.

I think a certain amount of time and miles are necessary to "break in" a new belt, though that wouldn't explain why yours was doing it with the original belt.   

I can only make somewhat ignorant guesses about your situation -- sorry. But then, even your mechanic hasn't figured it out yet either.  Maybe something is causing excess tension on your belt -- like maybe someone installed a stronger torque spring on the driven (rear) pulley?  Or, your pulley faces need cleaning -- there could be belt residue or some foreign substance on them causing the belt to stick a little?     

[djrider]

My People 250s makes a noise under quick hard accelerations, a fluttering sound, but much less now that I have some miles on the bike, 1550 miles, and since the break-in.
I asked someone f/Kymco about the noise under acceleration and was told its normal.
My belt would also squeal a little during take-offs but squeals less since the break-in. 
I also get a small surging vibration at lower speeds, around 25-30 mph and around 45 mph but its not bad and does not appear to be problem.
IMO the noise and minor vibration appears to be trivial to the way the drive train works on some of these.

 

[Yager200i]

Zen and djrider:
All that sounds to me like the symptoms of a belt that is too loose, not too tight.

The squeal, the fluttering sound, the surging at low speeds, the vibration, all sound like symptoms of a loose belt.

Perhaps your rear pulley's contra-spring is weak or broken? It may be that they didn't optimize your variator setup to ensure enough belt tension. Going with a stronger contra-spring and slightly heavier weights might give the belt enough tension to stop the slipping, while ensuring that you have the top end speed of the original setup.

A belt that is properly tightened generally won't vibrate except at very specific frequencies that are related to their tension (sort of like a guitar string), a harmonic, if you will. If you're accelerating, you'll fly past those frequencies so quickly that you won't notice them.

However, a belt that is too loose will vibrate most of the time, regardless of the harmonic frequency it is experiencing due to tension and speed of rotation. Especially when it's under a heavy load.

Although I'm no expert, I maintain hundreds of air handling units and fans that have belts ranging from AP16 to CX155 in size, ranging from one belt to 5 belts per unit. So I know a bit about belts.

[djrider]

Yager200i
Thanks for the input!
My bike is running much more smoothly now that I have over 1500 miles, less belt squeal and less fluttering sound under hard acceleration. Although, I do not usually accelerate hard taking off. Maybe its just mental and I am getting use to the sound of the scoot, etc.!
I am no expert but I believe it just needed broke-in to my style of riding? I ride smoothly with smooth take offs, no real quick hard accelerations at take off. Once the scoot gets moving then I will open it up once in a while. IMO I think a drive belt would wear-in under they style of riding and how one operates the throttle. Much like breaking-in a new clutch on a manual transmission! Hard, quick take-offs would be harder on the belt and smoother operation of the throttle would be easier on the belt IMO.
I still notice some belt squeal on take offs if the bike sits for a few days or if its damp or humid outside. Again, this could just be me or ironic! Otherwise I have less fluttering noise & less belt squeal than before. I purchased this scoot as a dealer demo w/approx. 70 miles on it so somebody else wore-in the belt before I got it!
I thought about what you said but I would think if I had a loose belt or weak spring the noises would be all the time and increase, not decrease IMO! I can't speak for Zen but my fluttering noise & squeal appears not to be major.
I will keep tabs on the noises and be mindful of what you said though. Thanks!
So far I am having a blast on my ps250!

[petertucky]

Mine makes the same noise under acceleration.  It doesn't sound necessarily harmful, but it is there.  I figure it is just a cute noise from the Kymco, gives it character.

I only have 600 miles on mine, so I will monitor as the scoot breaks in even more.

[Hoolander2]

Yes, do that pertucky, and welcome, by the way. Maybe you both are hearing just a little clutch slippage which wouldn't hurt anything.  The 500s are known for a squeal or growl from the clutch when taking off.  Some even do so at higher speeds when accelerating. I don't think it's ever resulted in any failures or real difficulty.  Just an annoyance.

[Rudolf]

My KYMCO GRAND DINK 250 squeeks when i stop the engine, the squeek is coming from the left side of the engine.

[Hermann]

Good evening... need some advise. I've got a 2022 Xciting 400i abs. Recently noticed, this rattling 'rrrrrrrrrr' sound, coming from the front and rear brakes, when applying them. The odometer stands on 3200km.....And with acceleration between 2000-3000 revs ....the scooter vibrates heavily, and goes away at higher speed. Im sure i could have heard some kind of strange humming sound. Very strange🤔 Any advise on this? Thank you so much for each and everyone's input.

Hermann