[swifty2014]

My old '83 has noise from the rear also but so much as a vibration. I even got another rear diff from ebay to replace it but it still has noises. I found a lot of noise from my transmission and gearing so it can transfer down the shaft and echo out that whole area. But a vibration , could be excess slack from the U joint or in the rear drive bearings. If you can put it up on a secure stand and run it slowly in gears you can listen with a piece of hose or stethoscope to pinpoint the sounds.
Also try to shake your rear wheel side to side to see if any slack is there. Possible wheel bearings.

 

[swifty2014]

Can you lift the whole bike and spin each tire and look for out of round? You may have a cord seperation if it is getting that much worse.
But is the vibration at wheel speed? If it is very rapid that could be the drive shaft since it turns about 3 to 4 times faster that the wheel speed, because of the gear ratio.
And when it is vibrating badly at speed did you try to pull the clutch in and let the engine slow down to feel the frame, suspension, wheel motion?
Just different ways to pin point a vibration source.

 

[swifty2014]

If the bearings are bad enough to cause a vibration it should show some looseness or side to side play it you can get the weight off the rear wheel. You can get a big screwdriver and hold it to your ear and spin the wheel and listen for bearing noises.

 

[swifty2014]

I worked on cars for years and always got suspicious when a customer said "I just had a tune up", or something similar, and their car was doing something unusual now.
So I would start by going over the previous work to see if that was the cause, and many times it sure was. I can't believe it either that a bearing would go bad suddenly and just 1000 miles since a tire replacement. Things may not have been put together back there correctly when it was apart. Maybe killed a bearing!
I AM SUSPICIOUS !!!

But this video cracks me up in the simple way this guy gets the old bearing out and so quickly, with a concrete bolt anchor =

https://video.search.yahoo.com/sear...720ac394cebd93a24db527047ad9663b&action=click

 

[swifty2014]

When the tire work was done was the rear diff bolts removed or the assembly taken off for some reason? If not I can't see how it would suddenly be a problem.
But make sure the previous tech has put all the spacers and washers in the correct place.
And you can put the axle through the bearings and put one end on the edge of a bench or in a vice, and hold the other end of the shaft, and spin the wheel by hand. Then you can feel the smoothness of the bearings while they have some weight on them as a double check. Also roll the axle on a table top to see if it got bent.

 

[swifty2014]

When the tire work was done was the rear diff bolts removed or the assembly taken off for some reason? If not I can't see how it would suddenly be a problem.
But make sure the previous tech has put all the spacers and washers in the correct place.
And you can put the axle through the bearings and put one end on the edge of a bench or in a vice, and hold the other end of the shaft, and spin the wheel by hand. Then you can feel the smoothness of the bearings while they have some weight on them as a double check. Also roll the axle on a table top to see if it got bent.