suggestions to find a vibration

[srteach]

I have a vibration that starts at about 70 and stays consistent with road speed from then on. It does not have a pulsing pattern and does not show up at low speeds. It seems to be from the rear (felt in the seat, not the handlebars). This is a high frequency vibration not consistent with tire imbalance.

I have put new tires on (internal balance beads) and serviced the final drive.

Does anyone have a clue to lead me to the elimination of the vibration?

[sandy]

You don’t mention mileage on your bike but I would check the U joint and the drive shaft splines at the pinion cup.

[Chrisj CMA]

I second u-joint. If it is the vibration will get progressively worse

[..]

I third that.

I hope you can see this.

https://www.facebook.com/groups/855896357793960/permalink/856098151107114/

[srteach]

Bike has 50,000 miles (98 valk). I was afraid it was the u-joint. I would have dropped the swingarm if I had the ujoint. I was already 90% there.
Propshaft splines are in good shape.
Time to gather parts. At least it should be easier than me mounting the tires.

[Chrisj CMA]

Bike has 50,000 miles (98 valk). I was afraid it was the u-joint. I would have dropped the swingarm if I had the ujoint. I was already 90% there.
Propshaft splines are in good shape.
Time to gather parts. At least it should be easier than me mounting the tires.

You do not have to remove the swing arm to remove/replace the u-joint

[Jess from VA]

Here's a nice link on the Ujoint (if it works).  Click the pics, and they get larger.

https://web.archive.org/web/20160523032210/http://www.rattlebars.com/mtz/ujoint.html



Besides Ujoint, maybe a wheel bearing.

The Ujoint thumps (pegs).  The bearing grinds/whines. 

[srteach]

You do not have to remove the swing arm to remove/replace the u-joint

I'm intrigued.  
How do you do that? Does the swingarm lift enough to access the ujoint?

GOT IT.
I read through the directions posted in the link to the rattlebars instructions. I'm gonna do it that way, it will save me time and money. Now to buy the ujoint (to have on hand just in case).

[Jess from VA]

If you open the Rattlebars link I posted above, it shows step by step how to access the Ujoint.

[srteach]

Got it. I edited my previous reply before I saw yours. Thanks to all who know more than me. I'm probably going to change the wheel bearings as well.