I agree with acquiring a Krikit II. Even though I ride an RTL, the concept is the same. My bike vibrated harshly, and I experimented with lowering belt tensions. I went through about half a dozen or more trials at getting it right. I landed right in a sweet spot once, (understand this is an RTL with a different setup) that didn't shake at any throttle setting or speed. I lost that when I removed the back tire, couldn't duplicate it. Found the lower I went in tension the softer the vibration was, and it also occurred at less speed. Finally got it in the 52 MPH range, just a soft fluttering on hills, and installed a Doc Humphreys (Roadster Renovations) belt vibration dampener. Smooth as all get out. I run the absolute minimum tension listed for an RTL, about 150 Lbs with the wheel on the ground.
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I'm including a screen grab of the TSB that Can Am issued in 2015. Basically it says lower the belt tension until the customer can live with the vibration. I just got my RTL back from the dealer, and my belt was over-tightened at 200Lbs. Apparently this is an unpublished rule in the Can Am repair circles, for nothing more than to further disappoint the customer. Looks life your bike needs somewhere in the 200 Newton range (lowest Spec), which will be around 45 Lbs on the Krikit II. One recommendation is to buy the service manual online for your model, or maybe for the 2019 model as Can Am is just now catching up on the manuals, and the new manuals list more information. In the back, under Technical Specifications, you'll find the drive section with the tension spec. It differs (on mine) from the information in the front of the book, and offers a little higher spec (for mine) than the TSB from 2015.