Modern Vespa

I recently installed the Polini variator kit. When driving at high speeds and release the throttle I hear a whirling sound almost like a spring sound. I cannot figure out what is causing this. As soon as I get back on the throttle it goes away. I can deal with the sound but I just want to make sure something isn't wrong. Has anyone experienced this?

Thanks

It sounds to me like you might have a belt that is slipping. In most cases when someone has changed a belt/rollers/sliders, the reason for strange noises during acceleration is either a wrongly torqued variator nut or the spacers/washers have been put back in the wrong order. I would open it up again and make sure the belt is correctly seated and everything is in the right order and torqued-up.

I bet the belt is hitting the idler pulley on the over-run. When you change the belt, always spin the idler pulley to ensure it turns extremely smoothly with no noise. If its bearing gets stiff or even seizes, belt wear can become very rapid.

Good morning and thanks for the reply. Just to confirm the bike is smooth and quiet during acceleration. I only hear the "boingggggg" sound when I let off the throttle at high speeds, as soon as I hit the throttle again the sound stops.

Thanks for your input. Sounds like I need to bring the bike back to the mechanic. What specific parts should I bring back to him to change or check? My mechanic does not store any parts, so I would have to provide him with any parts that may need to be changed. Bike has 2k miles and approximately 100 miles since installing the new variator kit. Thanks

We don't know exactly what the noise is, so it's not possible to give any better advice than guesses. Let your mechanic ride it, and see what he says - if he isn't experienced with your model, find a shop that is. I'd also be a bit dubious about any mechanic who doesn't carry a bare minimum of standard spare parts.

If you're not doing your own maintenance, it can get pricey chasing an 'unknown'.

May I ask how you like the Polini variator kit in general?

I'm considering one for my 2012 GTS 300.

Thanks,