Intermittent vibration

[tonyn]

I have a FJR with 104,000 kms and its got an intermittent vibration at 70 to 80 kmh , the vibration is a vroom vroom vroom sensation a bit like a tyre out of round ive experienced in cars and trucks before

Ive found side play in the shaft coming out of the back of the gearbox that the unijoints attached to , what I need to know is do I need to remove the engine to replace the rear bearing

 

[Bungie]

Before you start tearing into the bike, are you absolutely 100% sure your not feeling harmonics from the road? Are you testing this on the same stretch of road all the time? Does it do it other times on other roads?

The reason I ask is I experienced something similar on a stretch of hwy near my house. I inspected the bike and could find nothing wrong and was getting ready to let a higher power troubleshoot it. I just happen to go down the same stretch of road in my car and it did the same thing. Turns out somebody drove a bulldozer or some other kind of tracked vehicle down the road for a ways and the equally spaced 'dents' in the road caused the vibration.