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[heroto]

2018 S 7.2 with 2600 miles. Have had some warranty issues, new front wheel, tire and rotor, and just a few miles later, I just got it back with a new rear wheel, rear tire and belt. At 50 mph, it now has a vibration I can feel in the saddle, that fades in and out. The vibration is about 5-7 hz. It fades in and out on a 4 or 5 second cycle. It wasn't there before the new rear wheel, but my original rear wheel was out of round (manufacturing defect) and perhaps that broke up the resonance I'm experiencing now (?).
 
Moto seems fine otherwise.

Any thoughts that might help my dealer diagnose and correct this?
Thanks

BTW, I'm not crazy. I've owned and still ride many other motos and have never experienced this. It's not subtle.

[Curt]

If you have 140R70/17, the tire circumference should be 2*pi*(17 in+140 mm*.7) = 3.3 meters. At 50 MPH, the tire should be doing 50 mph/3.3 m = 6.7 rotations per second, corresponding perfectly with your 7 Hz butt-vibration-meter.

My guess would be that your tire is out of balance, which typically manifests at highway speeds. It might be one of:
- tire not fully seated on bead
- tire balanced improperly or not at all
- one or more balance weights flew off
- new tire is also defective

Why it would cycle on 5 second intervals is mysterious. Wild guess, maybe something loose inside the tire?
$0.02: Have the dealer remount and balance the tire.