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230 Head shake

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I have a 2003 230 and have recently performed the performance mods. It is running excellent, and I was running on a bunch of county roads this last weekend at Full speed and the front end has what my riding partner calls head shake. The front tire is shaking side to side rapidly and I am unable to stop it by arm strength. Looking for some advice if this is a worn tire issue, suspension, or just running faster on loose gravel. It wasn't slowing me down except for going into tight corners, and it's not bad enough to keep me from Wot. The tire has good tread, but is pretty old and has some weather checks. All help is appreciated.

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Replace tire with new (I always balance my tires but I'm one of the few)

True rim and tighten all spokes

Loosen all triple tree bolts, front axle and torque to factory specs with a torque wrench that is working properly.

IMO the problem is unheard of on a 230???

I suspect that all of the above will take care of the problem. Please,

Let us all know what you find out.

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Well I did everything except put on a new tire, and it still has the high speed shake. New tire will be here next week I will update when I get it switched.

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Before you pull the wheel check it for bad bearings and axial and radial run out while it is on the bike. With the bike on a stand grab the wheel and try to move it side to side, there shoud be no slop. Also slowly turn and check for roughness. Slop or roughness indicates bad wheel bearings.  Next slowly turn the wheel while holding a pen, pencil, etc at the center of the tread, you should observe no in/out or side to side wobble.   Next check one or both rim flanges. The results will tell you if it is the tire or rim. 

 

Also look at each side of the tire next to the rim flange; there is a small ridge molded into the sidewall.  It should be equal distance from the rim flange all the way around the rim.  I always check this when mounting a new tire. 

 

If the new tire passes muster then balance it.  I do this by prying the pads away from the rotor to reduce friction and then static balance the wheel.  I slowly rotate the wheel about 90 degrees and then watch which way it settles, do this several times and you can find the heavy spot.  Add some weight to the opposite side, and repeat until you can no longer detect a heavy spot.  With used bearings and seals this will often be less than 1/2 oz out of balance, more than adequate for a dirt bike.  I use adhesive weights for alloy car wheels.

 

The above usually fixes head shake/wobble unless caused by suspension set up issues.

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Finally got a new front tire and now the head shake is gone completely. Conclusion is the tire was causing the problem. Thanks for the help.

CFR 230F, KX250

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So just the wheel was shaking back and forth or the whole front end assembly, wheel, forks, handlebars etc. ?

 

This can also happen due to steep rake, the forks are more vertical than laid back.

This can happen when fork springs are too soft and/or rear is too high.

If it had more head shake on decel this is likely due to rake.

Is the new tire taller at all?

We are only talking about a couple of degrees between head shake and none.

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So just the wheel was shaking back and forth or the whole front end assembly, wheel, forks, handlebars etc. ?

 

This can also happen due to steep rake, the forks are more vertical than laid back.

This can happen when fork springs are too soft and/or rear is too high.

If it had more head shake on decel this is likely due to rake.

Is the new tire taller at all?

We are only talking about a couple of degrees between head shake and none.

 

Agree.  All of these contribute to head shake but in the OP's situation tire wobble was initiating it and the steering rake and trail were not able to dampen it out.  I've had out of balance tires cause up/down vibration but not wobble, (knock on wood). 

Years a go I had a 250 2T that would wobble every time at the end of a long straight away, disconcerting but not a problem.

I had a another bike that never showed signs of wobble but spit me off after a front wheel landing in top gear.   Three broken ribs and a separated sternum made me adverse to wobble. :banghead:

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I had a totally tricked out 89 RMX racer. At 70+ you would chop throttle and hold on. Tried steering dampner and it helped but at 85 or so I was putting my life in jeopardy. At national 4 day qualifier I was talking to Team Suzuki and they showed me thier fix. Cut frame and add 1-2 degrees more rake. Solved problem. Later models were changed. They said it was too steep even for eastern enduro and that bike was dangerous when I took it to sand dunes til I fixed frame.

 

Glad tire fixed yours. Never had tire cause headshake. I also never use a worn tire up front. Always best and new. Rear I will abuse but front end washout crashes are very very bad.....

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So just the wheel was shaking back and forth or the whole front end assembly, wheel, forks, handlebars etc. ?

This can also happen due to steep rake, the forks are more vertical than laid back.

This can happen when fork springs are too soft and/or rear is too high.

If it had more head shake on decel this is likely due to rake.

Is the new tire taller at all?

We are only talking about a couple of degrees between head shake and none.

The head shake I had happened only at high speed and on gravel roads that were a little loose. The handle bars would go back and forth with with enough force that I couldn't stop it. Slowing down 10 mph and it would go away. Also it wouldn't happen while on an asphalt surface only on the gravel road.

I torqued the triple clamps and the front axle to spec, and loosed all the spokes and torqued them all back to spec. Took a ride between each adjustment and all turned out with no improvement. After I replaced the tire I no have no shake.

I didn't measure the old tire, turned out it was the original factory tire, but this new tire does seam to be a little taller. That may have changed the rake angle. I am planning to do some more adjusting, like moving my forks up in the triple clamp and see if that will cause it to happen again. I will update when I know more.

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Changes in ride height at either end will change steering rake. A 1 inch change in ride height at one end on a 58" wheelbase bike will result in approx 1 degree of change in rake.  This is one reason rider sag is so important, or a front wheel landing can cause  a high speed wobble.

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The head shake I had happened only at high speed and on gravel roads that were a little loose. The handle bars would go back and forth with with enough force that I couldn't stop it. Slowing down 10 mph and it would go away. Also it wouldn't happen while on an asphalt surface only on the gravel road.

I torqued the triple clamps and the front axle to spec, and loosed all the spokes and torqued them all back to spec. Took a ride between each adjustment and all turned out with no improvement. After I replaced the tire I no have no shake.

I didn't measure the old tire, turned out it was the original factory tire, but this new tire does seam to be a little taller. That may have changed the rake angle. I am planning to do some more adjusting, like moving my forks up in the triple clamp and see if that will cause it to happen again. I will update when I know more.

Gravel sure does give an uncomfortable floaty feel to my bike.

What tire do you have on the front now?

Moving the forks up in the triple clamp will decrease rake and could bring the wobble/shake back.

 

Changes in ride height at either end will change steering rake. A 1 inch change in ride height at one end on a 58" wheelbase bike will result in approx 1 degree of change in rake.  This is one reason rider sag is so important, or a front wheel landing can cause  a high speed wobble.

Yes indeed!  I'm really starting to realize just how important proper sag is.

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MetricMuscle - I put the IRC VE-33 which I read about on this site.

CFR 230F, KX250

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MetricMuscle - I put the IRC VE-33 which I read about on this site.

CFR 230F, KX250

Thats a rear tire.

I have a brand new one of those I'm gonna try soon on my rear.

I have a Bridgestone ED-11 front tire at the moment, really like it.

You must have an IRC VE-32 or VE-35.

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Gravel sure does give an uncomfortable floaty feel to my bike.

 

I think that is called a feature, not a bug. Best solution that I've found is to put my butt back over the rear axle, and gas it.

Then, of course, you are uncomfortable because you are going too fast.

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