Slight vibration at speeds above 60mph SOLVED

[An Orange Crush]

2011 DT300i 17000 miles
Smooth acceleration up to speed then when I back off the throttle and settle in at speeds above 60 (indicated) I feel a vibration coming from beneath me.
The belt (OEM) has less than 200 miles on it (vibration was noticed before belt change) tires both less than 2000 miles and have good tread. I use Dynabeads in both tires and have been running 14 gram DR Pulleys without issue but I did notice some dark markings on some of them like from a Sharpie marker when I changed the belt, however they each weighed in right at 14 grams so I put them back in.
I cleaned everything up good before re-assembly but there again, the vibration was there before I changed the belt.
The new belt puts me to 5400-5500rpms @60mph and around 6400rpms @ 70mph whereas the old belt ran at higher rpms plus there was that vibration. I thought a belt change would lower the rpms which it did and hoped it would smooth the ride out at higher speeds but it didnt.
I`m going to order a new set of sliders since they have those marks on them but always open to any other ideas.

[CROSSBOLT]

I have had two DT300i scoots and vibration has not been normal. I, too, have used Dynabeads and now use BB's. The only thing that comes to mind as a remote possibility is the front pulley, the variator. What I'm getting at is, didja get that belt all jammed down in the clutch (rear) pulley as far as you could before your fingers fell off? This is to produce as much slack in the belt so the pieces of that front pulley can be solidly seated when that front nut is torqued down. Bad things happen if any of those pieces are loose.

[An Orange Crush]

Yup I sat down on the ground and put both my feet on the rear clutch and used both hands to pull the belt in. I was pretty sure it was open all the way and belt completely seated. But I will take another look to be 100% certain.
The vibration actually started before this latest belt swap though and nothing seemed out of the ordinary during the change~ when I took the nut off the variator it was good and tight.

[mousejunks]

Is it possible for you to take a video of the transmission with the cover off while accelerating on the centre stand?  Similar to this: . The vibration may be due to late shifting or belt slack.

[CROSSBOLT]

Could be one of the rollers is sticking in the track?

[Stig / Major Tom]

Steering head bearings, engine bushings, rear wheel bearings, exhaust tight? Tire bruised? 
(throwing oatmeal against the tree here from my sidewalk table)
Stig

[An Orange Crush]

I will give all the above a shot when I get my new parts in for the CVT.
I ordered some new sliders seeings how the ones I have in there now showed some black marks on them when I replaced the belt last week 8-2-2019.
I will especially be sure to torque down everything having to do with that exhaust too.
It has gotten louder over the years and it might just be part of the problem, along with engine bushings and the rear wheel bearings~ thank you for those suggestions Stig and you are right, that exhaust might just be it.

[An Orange Crush]

The issue turned out to be a pretty simple matter of two things. Number one my scoot sits for a few months every year for winter and I believe I wasnt putting enough miles on at each ride this year to distribute those Dynabeads. I think the minimum is around 5 miles?
And my rides were always short and right around that amount until one day I rode a good 20 miles and noticed it smoothed out significantly towards the end.
The 2nd and embarrassing item is the front tire was 3lbs low on pressure and the rear was about 6lbs low on air. When I corrected this 99.9% is gone.
The end of riding season around here is right around the corner so its time for fall color rides, enjoy everyone