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flybyu

speed wobbles

18 posts in this topic

I get speed wobbles on my '01 at high speeds...handle bars start shaking back and forth to the point where I'm out of control (though some would say I'm always out of control) . It's not a comfortable feeling to say the least. Last time it happened it cost me a perfect day of riding and a visit to the emergency room.

Anyone have advice on where to start to get rid of the wobbles???

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really? you don't think it's anything to do with the tuning of my front wheel or my forks being crooked, etc?

I haven't experienced the wobbles to this degree on the 2-strokes I've had in the past.

what is the correct body positioning you're referring to?

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Speed wobbles are caused by a few things,

1: the Shock may be in need of repair

2: The back wheel is up to far forward on the bike

3: Swing arm is loose, beering s bad ect

The lenght of the bike is a big factor along with steering rake.

Questions

1: Front End Stock

2: How many links in the chain 120 is stock

3: How far up is the rear wheel in the swing arm.

If the front end has a steeper rake meaing degrees out from 90 this can caus eit if you have not compensated for rear wheel lenght (aka Axel to Axel)

The speed wobble can be caused also by the rear shock if it is in bad shape... Leaking oil or just plain wore out

grab your rear wheel from the farthest position back and try and see if you can move it or if there is side to side play in the swing arm or wheel beerings them selves

Somting is definnetly not right back there

[ May 06, 2002: Message edited by: EgoAhole ]

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Play with your fork and shock clickers. With the stock settings my head-shakes like an SOB. I tightened up the rebound and compression quite a bit and set the sag properly for my weight and the head shake went away completely.

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Most people think that "Head Shake " comes from the front end. Some times this is true but MOST of the time , headshake is actually caused from the rear end!

The rear may be "PACKING" .......speed up the rebound.

Or the rear may be set TOO stiff of a compression setting.

Soften up the front til' you are comfy with it NOT bottoming then work with the rear.

.

:D

Either way .......try this too.

You probably spent as much on parts/bars/ER :D

as you would have if you would have bought one of these>>>> IM000612.JPG

:)

IM000613.JPG

Trust ME ....been there done that!

:D

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FREESTYLE........

I would have to agree with YOU!

only my instance is to try ANY suzuki!

in particular a '93 RM 250!!!!!! :)

I nicknamed it "DEATH" :D

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No no No no NNNOOOOOOOO

The Susuki RM 400, That lil widow maker would swap ends at the flick of the throttle, and if you could keep it in a straight line

No one could, that was the most dangerous bike I have ever seen and had the displeasure of riding.

I got into such a speed wobble on that my head is still bruised....

Maybe that splains things :)

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Headshake

Comes from the forks being to soft on the compression, try turning the compression clickers in 2 clicks.

or

Another possible headshake cause is Steering head bearing are loose.

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I had some head shake before I had my suspension done. I noticed after having it done at Enzo, it was way stiffer. I noticed the headshake believe it or not, during hard acceleration. It was kind of un-nerving, trying to hang on to that beast pinned in third and going to fourth with the headshakin like it was. But it disappeared when the fork got heavier springs and stiffer dampening.

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That's weird! I was going to suggest softening up the suspension. You guy's are saying mostly to stiffen it up. I would get headshake at high speeds with my desert settings (stiff). I eased up on the compression clickers and it gradually went away. I run my sand dune settings (soft) and there is virtually no headshake. I have pics of going down the wall in Dumont in fifth with no hands. In any case, a steering dampener (Scotts in the best so far) will cure headshake at whatever stiffness.

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is 'head shake' the same as 'speed wobbles'? forgive me if this is an ignorant question.

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nothing will fix 93 cr250 headshake.i tried everything the fork rake is just to steep.i still have the bike.it turns great and i love jumping with it.i dont ride it much anymore,i get more entertainment out of letting my friends that dont have bikes borrow it when we go riding.sometimes headshake will get so bad it throws you off bike.my+1993+cr250r---1.jpg?bcMpR28Ana3nSJfj

[ May 07, 2002: Message edited by: freestyle111 ]

[ May 08, 2002: Message edited by: freestyle111 ]

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Flybyu,

Assuming that your bike's in mechanically good shape, the main effect on hi-speed stability comes from the effective steering head angle/rake. More rake equals more stability; less rake equals better front end traction, especially in tight corners.

You make can make both static and dynamic adjustments to your effective head angle by:

Static Adjustments:

Rear Sag - more sag equals more rake and stability Fork Hgt- raising the forks in t-clamps reduces rake and stability, but aids turning.

Dynamic Adjustments:

Fork Clickers: More Compression or Less Rebound keeps the fork higher in the stroke providing more rake and stability.

Shock Clickers: Less Compression or More Rebound keeps the shock deeper in the stroke, effectively increasing sag and providing more rake and stability.

I recommend making sure that sag is set to 100mm and that your forks are flush with the top of the clamps. From there try playing with the clickers. Assuming that you don't want to make your ride stiffer, I would start by backing off 1/4 turn on the Shock Hi-spd Compression. Then try taking 1 or 2 clicks out of the Fork Rebound.

Steve

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FlyByU

Yes HeadShake and a speed wobble are two entirly diff phenominoms

as vznx1w Points out very nicely the effects of Speed Wobble

the main effect on hi-speed stability comes from the effective steering head angle/rake. More rake equals more stability; less rake equals better front end traction, especially in tight corners. You make can make both static and dynamic adjustments to your effective head angle by:/QUOTE]

He also notes on some positive feed back on trying to reduce the effect of the wobble

Hence head shake and speed wobble are two distinct beasts.... :)

This adjustments also reduces the lenght between axle to axle

te short the distance the more likly the wobble and severity. the long the distance the less likely wobble but you sacrice turning radious due to longer axle to axle.

Next time you have a chance watch a Dirt Track Mile these guys are on the very edge of the envelope when it comes to head shake / Spd Wobble

Head shake is more defined as the bike is excelerating hard, less wt up frnt less tracktion

the wobble occurs as the bike begins to break its stability point at speed, its another gyr effect, DAMN PHYSICS....Mainly half way to 2/3rds down the straight you will see the bike begine to twist front back thats the wobble.....

wathc the bikes exit a turn wil show the handle bars shake some what thats the head shake.

Lowering the forks down will reduce head shake. it allows the clamps to grab down further effectivly shorting the rake/trail and stablising the forks.....

Now I can go on and on but those that have an IQ of 140 will object :D Call it what you will, but my experiance in years past tuning for mile / 1/2 mile and 1/4 mile along with me RR's. I experianced alot of both........... :D

[ May 08, 2002: Message edited by: EgoAhole ]

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Jeesse Ego, Im not going to object! Hell, my little green streak used to speed wobble like hell at the end of the straight, when I was riding TT back in the day. It would wobble like hell after about 60mph and about 70 I almost couldnt hang on, until I finally got it kicked over sideways and could get some rake in fork with the slide. Sometimes you could use the wobble to help yo intitiate the slide, that is as long as it wasnt zinggin, when you were trying to zag it.

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