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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: GasStation on April 20, 2012, 11:18:00 PM

Title: 93 K75S - Handlebar vibrations/oscillations
Post by: GasStation on April 20, 2012, 11:18:00 PM
Do your handlebars start shaking in resonance, that is the amplitude increases unless corrected by holding them, when both hands are off the handlebars while riding?

I know, I know, I don't/shouldn't ride without my hands off the handlebars.  :lol:  :loco:

I had both hands off only a few inches above the other day and some sort of rattle or shaking left to right was rapidly developing to the point that if I did not intervene, the front end would have went into self destruction.

Any thoughts on what is the origin of this? Steering damper? Bearings? Fluid bloc assembly? Front wheel? Forks? :confused:
Title: Re: Handlebar vibrations/oscillations
Post by: frankenduck on April 21, 2012, 12:29:19 AM
It would help if you put your year/model in your profile sig. (Hint, hint.)

Usual suspects are:

Tire tread cupping.
Loose steering head bearings.
Weights fell of and your front tire is out of balance.
Title: Re: Handlebar vibrations/oscillations
Post by: GasStation on April 21, 2012, 07:06:18 AM
It would help if you put your year/model in your profile sig. (Hint, hint.)

Usual suspects are:

Tire tread cupping.
Loose steering head bearings.
Weights fell of and your front tire is out of balance.
Done, it was late. I rarely omit that important detail. Thanks.
Title: Re: 93 K75S - Handlebar vibrations/oscillations
Post by: mystic red on April 21, 2012, 04:09:34 PM
No GS, Duck meant in your signature, located under your profile (http://www.motobrick.com/index.php?action=profile;u=726), then on the left click on "forum profile" and type your bike year/model in the signature box and then click "save profile" at the bottom of the page. Then you won't have to remember to start every thread with it. :biggrin: Unless you just want to.
Title: Re: 93 K75S - Handlebar vibrations/oscillations
Post by: GasStation on November 04, 2012, 12:53:47 AM
I am going to revive this topic since the handlebars are surprisingly quick to vibrate out of control unless there is weight on the bar ends, ie. my hands.

The tires do not show any unusual tire wear. The front tire still has the balancing weights. I am not familiar with the possible steering bearing being loose or warn out. Is this normal for a bike with 45,000 miles? What about the fluid bloc steering damper. I did muck around in the area last winter. Could it be that the fluid bloc assembly moved and is causing this type of resonance?
Title: Re: 93 K75S - Handlebar vibrations/oscillations
Post by: wmax351 on November 04, 2012, 01:33:23 AM
I am going to revive this topic since the handlebars are surprisingly quick to vibrate out of control unless there is weight on the bar ends, ie. my hands.

The tires do not show any unusual tire wear. The front tire still has the balancing weights. I am not familiar with the possible steering bearing being loose or warn out. Is this normal for a bike with 45,000 miles? What about the fluid bloc steering damper. I did muck around in the area last winter. Could it be that the fluid bloc assembly moved and is causing this type of resonance?

Fluidblok is pretty useless at speeds. Its really only for low speed.

Was the tire balanced when it was put on?

Steering bearing could do it. Or just dried grease in the steering bearing.

Bent frame/forks/etc is an option. Has it been crashed?

Steering bearing is the most likely option. Could be loose, Worn, or have dried grease.

A K75 should be completely stable at all speeds.
Title: Re: 93 K75S - Handlebar vibrations/oscillations
Post by: Rick G on November 04, 2012, 01:44:20 AM
I have seen an underinflated front tire cause it.
Title: Re: 93 K75S - Handlebar vibrations/oscillations
Post by: ReneZ on November 04, 2012, 04:15:08 AM
Indeed, with a resulting cupping of the tyre.