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SM On The Freeway - 80+ MPH Steering Wobble

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2005 Husaberg FS650E

It's not an up/down oscillation I would attribute to an imbalanced tire but more of a steering wobble.

Just checking to see anyone else with SM bikes who occasionally hit the freeway also experience this slight front tire wobble at or above 80mph.

Not sure if I should attribute it to the aerodynamics of the mirrors/handguards or the short 17mm triple clamp offset or all of the above.

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I havent experianced this on the Bergs Ive owned and my KTM doesnt do it either.

heres a couple of ideas...

Worn steering head bearings? If you wheelie as much as I like to,this could be an area of interest if youve got a few miles.

Rain grooved freeway??

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I get the same thing on both my bikes, YZ450 and a KTM450sx though it seems to only happen when I'm on the gas and picking up speed. I've found that getting more weight forward while trying to get out of the wind (as much as possible anyways) helps some :banghead:

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I get the same thing........... though it seems to only happen when I'm on the gas and picking up speed. I've found that getting more weight forward while trying to get out of the wind (as much as possible anyways) helps some :banghead:

Same here on my WR426. When i'm in top gear, accelerating hard, the front gets a little twitchy, especially riding into a headwind.

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Do the wheels have single rimlocks? If so, they require balancing. :banghead:

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Your front tire isn't clapped out is it? I noticed my bike has some headshake under certain conditions after taking my tard out on the street with clapped out track tires that are really worn out on the sides but perfect in the center. (Call me cheap, but I couldn't bring myself to throw them away.)

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Suspension setup / sag / ride height makes a big difference on the issue.

Also try to not pull back on the bars as you are going along. Put as little pull on them as possible. That usually helps the bike stay stable.

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Also, at that speed with the geometry of the bikes we ride, the wheel alignment will make a big difference.

If your rear wheel is offset to clear the chain thats one issue.

If the forks are twisted ever so slightly in the triples that compounds the prob.

If the rear wheel is is not perfectly in line with the centerline of the bike that adds yet another dynamic.

Even if the rim is slightly offset it can be pointed left or right after you tighten your chain or replace the tire for example.

Computrack can get all that squared away for you and mark the swingarm after they shoot the bike so that everytime you replace the rear wheel you get it right, but these are things you don't normally notice at slower speeds which are accentuated at higher sustained speeds, it's an oscillation or a harmonic that builds on itself.

Some suspension adjustments can minimize the effects but the problem will still exist if the bike is out of alignment.

Another good idea is to get 2 household bathroom scales and place the rear wheel on one and the front wheel on the other.

Combine the weights to get a total overall bike weight.

Do the math to get percentage of difference between the front and the rear and then adjust the ride height in the back and or drop the forks in the clamps to get the bike to 60% rear and 40% front weight distribution and you are at the "theoretical" perfect balance for your machine.

Small adjustments make a significant difference sometimes,

Scream

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I played around with the bar settings on the Katoom today and was able to get the wobble (headshake) you mentioned.

It seems the farther back I rotated the bars,and the farther back I was in the saddle made a noticable difference.

I only scooted back maybe an inch on the seat to compensate for the bars being further back and got the wobble under hard acceleration from a stop as well as hard acceleration from 80+ mph.

Im sure the other things mentioned could be contributing factors,but,in this instance the culprit seems to be weight distribution.

Hope this helps.

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I'm with the guys who recomended proper suspension set up.....all three of my SM's shook to some degree till I set the sag and played around with the front :banghead:

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ya ckeck the susp settings,my drzsm sometimes does the same thing,i was told to put some heaver springs in the front.the more the front compresses the shorter your wheelbase gets thus making it a little unstable at 70 or 80mph.gusts of wind don't help either

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Robbie,

As we discussed last weekend,

Ditch the slicks on the street. That was the single biggest factor for me in high-speed 'wiggle'.

Thanks again for the pilot powers. Great tires, nearly as sticky as my slicks, no high-speed wobble, highly recomended!

Also, I'm in the process of making slight tweeks to my forks to get everything setup correctly for my riding. This has also been a factor in eliminating high-speed headshake.

One last note...

When I first put my bike together I rode it for a few days without the steering damper. It was a little spooky at high-speeds. After fitting the Scotts it's a whole 'nother animal.

Oh, and move forward on the seat!

Good luck!

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Anybody ever consider that maybe the front fender is oscillating in the hurricane force gail at 80mph? It would take 3 mins, 4 bolts, and 1 ride to eliminate that possibility. But I think it's a pretty good bet. Remove the front fender, go for a spin down the hywy, then come back and tell me to shut up!! The steering damper would fix the problem, but it's an expensive fix for a bike that's not suposed to go on the hywy to begin with.

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It might be a "Death Grip" thing. Relax your hands on the bars. Realxing your hands on the bars helps diminish the effects of the wind acting on your torso. Also scoot forward on the seat.

The high front fender is also a contributer.

You might try and learn to enjoy it...it what makes it fun to do 80mph. Hayabusas never wobble at 80..that's why they are boring until you hit 150 and that's why Sm's are a blast.

Chris

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what tires are you using? Some guys here in the UK were having the wobble on their KTM's using maxxis goldspeed tires. Once changed the wobble went away. So maybe check you tyre pressures first and then next time you need new tyres try changing brands

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I use Dunlop radials on my Berg 501SM.

She is rock steady on the open highway through the gears to a top speed of 93mph, she does not shake or quiver at all.

Very pleased, very happy with the high speed stability of the Berg.

Now on my 03 GL1800 is a different story, I had a bad head shake at 40mpg.

It was so bad that when you let go of the bars they shook violently, it scared the shit out of me.

I would not ride the bike in fear of a failure, something was wrong....

So working with my local Honda Dealer, we checked the the tires and rims, adjusted the suspension up and down, tire pressure up and down and we tracked the problem to a dent in the lower steering head bearing race.

When the bearing moved over the dent in the race, the bearing would get stuck in the race and cause the wobble.

Both sets of bearings were replaced on the 1800 and the wobble was gone.

The 1800 was repaired under warranty, but I was told to keep both wheels on the pavement. :applause:

The next time you have the front end appart on your SM, take a close look at the steering head bearings, make sure they don't have a dent in the race and they move freely. Reassemble the the triple clamps to factory specs and make sure you have the forks installed evenly.

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Something that hasn't been mentioned is the fact that your headstem bearings might be too tight. If they are just a little tight they can cause that exact kind of wobble.

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Something that hasn't been mentioned is the fact that your headstem bearings might be too tight. If they are just a little tight they can cause that exact kind of wobble.

Good point! In addition to potential wobble, steering head bearings that are too tight also lead to steering irregularities such as "numb" steering and problems while turning corners. :applause:

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