This morning when I left the house I forgot to zip the sleeves on my jacket so I let go of the bars to zip them up and the handlebars started shaking so violently I almost lost it . After I came down from my adrenalin rush I tried to reproduce it. If I get up to 50 mph and let go of the bars it's fine, as the bike slows to 42 the shake starts, at 40 mph its out of control. If I hold the bars lightly to keep it under control it goes away at 35 mph.

So I guess it's a trip to the dealer today. I'm guessing it has something to do with the tire or the balance of the tire.

Anyone else ever experience this ?

 

That's just the demon trying to get out.

 

First thing I would do is check the tire pressure....even a few pounds low can cause problems and especially now (at least here in Wyoming) where the temps are getting cooler at night I find my tires loose a couple pounds a week just sitting in the garage between rides.

 

That phenomenon is a common occurance on motorcycles. I have had it occur on almost every bike I have owned in certain situations. Here is some info from (gasp!) Wingworldmag.com that I think explains it pretty clearly

The Tank Slapper
The most often complained about handling quirk is a handlebar oscillation that’s referred to by many as a “tank slapper.” This condition, which has a frequency range of eight to ten cycles per second, normally occurs when the handlebars are released while the bike is coasting down through some speed between 45 and 35 miles per hour. The handlebars will behave like a fluttering shopping cart wheel. As it begins, the handlebars begin to wiggle from side to side with the arc widening very quickly. If the hands aren’t quickly placed back on the bars, the bars will oscillate quickly from lock to lock, sending the machine out of control and the rider to the ground. While overly loose stem bearing adjustment will aggravate this condition, it is not, in itself, the cause of it. The degree to which any bike is prone to exhibit handlebar oscillation is linked to the size of the wheel/tire assembly, the rake and trail dimensions, the total unsprung weight of the front end, and the natural frequency of that unsprung weight. It is also affected by tire/wheel runout, tire imbalance, loose steering stem bearings, loose swingarm bearings, loose wheel bearings, loose engine mounts, worn tires, and tire pressure. Regardless of the existence of the above maladies, a bike will not normally go into a tank slapper while your hands are on the bars providing the necessary damping.
Many different makes and models of motorcycle exhibit handlebar oscillation during coast down at around 40 mph with hands off the bars. This is because the frequencies of the oscillation and of the wheel imbalance or runout come into line, while gyroscopic stabilization of the wheel is low. If you insist on removing your hands from the bars in an attempt to produce this symptom, and if you refuse to accept its presence, check and adjust all of the points mentioned above. If all is well but you still aren’t satisfied, you may wish to consider installing a hydraulic steering damper on your bike. However, the last thing you want to do is intentionally over-tighten the stem bearings to provide additional hands-off damping.

 

The Stealer...err Dealer will say ther e is nothing wrong and we cannot duplicate this problem as our insurance will not allow our techs to let go of the handlebars...... I have however noticed that when heavily loaded with all camping gear and the OL sometimes this will happen as I let go and stretch every now and then.... put some more PSI in the airshocks seemed to help out .

 

You don't have a Guardian bell do ya?

But seriously though take it straight back to the dealer!

 

Went to the dealer today to make an appointment to have it looked at. First thing they said was the neck bearings were loose (I knew that would be their diagnoses) and buy the way it's not covered under warranty.

Personally I think it has something to do with the wheel or tire as it only happens in a narrow band of speed.

 

Neck bearings. Not covered under warranty?
I call BS on that!

 

I believe loose steering head bearings would be considered under normal wear and tear and an adjustment would not be covered under warranty, besides, even if everything was within factory specs your bike may still do it, many of my bikes over the years have had this issue, including Japanese sport bikes with premium suspension components.

If you find yourself needing to make some kind or clothing adjustment set the cruise control to maintain a steady pace and you should be fine, it's the deceleration that creates the problem.

 

+1 especially on an 09. The dealer should be jumping to resolve the issue...