Head shake

[yamaha250F]

At the track today breaking bumps developed at the end of a long straight away. While slowing down after the straight I got huge head shake. My bars where flipping back and forth so much it was just a blur, i could not steer at all during this. What do you do when you get this? Lean back? Fowrard? Brake? And also how do you exelerate on these it seems really tough to get speed for a jump when these things are right before it. I dont think I whant to go as far as a stearing stablizer but some tips to reduce this sure would help. Thanx

[Bman]

Two words


Scotts Damper.

[Keetoman393]

Originally posted by yamaha250F
At the track today breaking bumps developed at the end of a long straight away. While slowing down after the straight I got huge head shake. My bars where flipping back and forth so much it was just a blur, i could not steer at all during this. What do you do when you get this? Lean back? Fowrard? Brake? And also how do you exelerate on these it seems really tough to get speed for a jump when these things are right before it. I dont think I whant to go as far as a stearing stablizer but some tips to reduce this sure would help. Thanx

Sounds like you may need to adjust your dampening a little bit. If it kicks like that, it's either rebounding too quick or the compression damper is set too stiff and you are deflecting.

[Madman393]

Originally posted by Bman
Two words


Scotts Damper.

I second that! I had to run without mine today as I mangled the mount in my crash last month and I felt naked and not nearly as confident.

Head shake is caused by the front end oscilating. You need to brake this when it occurs by pinning th throttle if you can or standing on the brake. Weight to the front helps if you need to slow down. If at high speed with a run in front, I will pin the throttle, get the front end light and get the bars back into control. As mentioned, it sounds like you need to make some compression adjustments to the front end.

[yamaha250F]

If I change my suspension will it lack anything for the jumps turns and whoops?

[JohnLorenz]

Alot depnds on
Your weight
your Ride Style
your Bike setup

and what you are comfortable in doing, I know the yamahas have a bit of a shake but not as violent as you describe.

Will a damper work, probably some but I think the underlying issue is suspension.

Need to know more info such as how heavy are you with gear?
Did you do any setup to your suspension?
What is your riding ability?

Here is a good link in setting up the rear and front

[Only registered and activated users can see links. ]
Take note in the last paragraph regarding head shake

Please read through this carefully it has some very good information. Then come back with some question

Hope it helps good luck

[crmx91]

if you get head shake just lean back and clip the throttle once.. it will allow you to get it under control.. i wouldnt lean forward if you have headshake.. it will spit you over the bars..

[Dell30rb]

The best way to eliminate headshake is to lengthen the wheelbase. Start by lowering the forks in the clamps, go in 5mm incriments, and if that does not take care of it put the fork caps flush with the top TC.

If lowering the forks does not take care of it, you can add a link to your chain and run a longer wheelbase.

[FFRacing]

Dell, lengthening the wheel base will worsen the headshake. It is not as simple as some would think. Making the wheelbase longer puts more weight on the front end, making the problem worse. 99% of the time headshake can be cured by proper suspension setup. A damper is not intended to CURE headshake. It is for the occassional time when for no apparent reason, the rider needs some assistance controling some shake. Matter a fact, when a damper is setup properly, the rider should feel NO resistance from the damper. TW

[Madman393]

Originally posted by FFRacing11x
Dell, lengthening the wheel base will worsen the headshake. It is not as simple as some would think. Making the wheelbase longer puts more weight on the front end, making the problem worse. 99% of the time headshake can be cured by proper suspension setup. A damper is not intended to CURE headshake. It is for the occassional time when for no apparent reason, the rider needs some assistance controling some shake. Matter a fact, when a damper is setup properly, the rider should feel NO resistance from the damper. TW

I agree with your dampner statement. When I run mine, I use only high speed and have the low speed all but disabled. In the instances of violent head shake that I have encountered, it has often come at high speed with a energy input to the front end that sets up the oscillation. This is where the dampner can intervene before the oscillation even develops.

[jmiakaike]

Originally posted by FFRacing11x
Dell, lengthening the wheel base will worsen the headshake. It is not as simple as some would think. Making the wheelbase longer puts more weight on the front end, making the problem worse. 99% of the time headshake can be cured by proper suspension setup. A damper is not intended to CURE headshake. It is for the occassional time when for no apparent reason, the rider needs some assistance controling some shake. Matter a fact, when a damper is setup properly, the rider should feel NO resistance from the damper. TW

just trying to figure things out for him... guessing bascially...lol

he said he got the head shake at the end of a long straright with braking bumps..., it is possible that he has too much rebound damping and his suspension may be packing a bit... , which started the shake

just a theory, hard to diagnose without seeing you ride it...


James

[mat bow]

always,always,always gas it when in doubt,speed got you in trouble speed will get you out.But don't blame me if it don't work lol
Mat

[Florida 393]

I am stating out of this one. last time I got into a frame geometry discussion I got publicly humiliated and I left a board for a couple of days. Y'all have a good discussion and I hope some questions get answered.

Bill

[jmiakaike]

Originally posted by Florida 426
I am stating out of this one. last time I got into a frame geometry discussion I got publicly humiliated and I left a board for a couple of days. Y'all have a good discussion and I hope some questions get answered.

Bill

Bill

you know it isn't the same here... i throw out my thoughts, and if someone can give me a good explanation of why i am wrong, then i will admit that i am...lol and it is so difficult.as you know, to diagnose something like that..
all we can do is give him some causes of the problem, since many things can cause that, problem.. from overly stiff, overly soft suspension, a flat tire etc...

come on back bill!!!!

james

[yamaha250F]

Naw my PSI was right on. I checked it at the track. But I was running it lower than usualy b/c muddy conditions. However, this could not cause massive head shake. My suspension is stock, im going to try to go 2 clicks softer and set a sag.

[Florida 393]

That post was meant in jest. sorry if I caused a problem. I will not be posting on this topic however.

Yes it is a different world here, thank goodness!!

Bill:

[Dell30rb]

What do you guys think running the forks flush in the clamps as opposed to raised up a little does to the wheelbase?

I may be wrong, but I swear I heard someone say to add a link to your chain if you have exhausted fork possibilities. I have thought that to be true for a long time, and i guess I reasoned it was true because of the above.. well.. reasoning.

Mabye that person was bill...

[FFRacing]

raising the frontend does a few things...
increases rake
increases trail
puts more weight on the rear
increases swingarm angle
forks will have more stiction

lengthening the wb by adding links
steepens rake
decreases trail
puts more wt on the front
increases the leverage ratio on the rear shock

One of the most common reasons for headshake is not having the fr and rr suspension "balanced" ie. front too stiff and rear too soft etc.
2nd reason is having the steering head bearings misadjusted or they are worn out.
Like I said in a previous post, a damper will not cure chronic headshake. It is there to help out for the occasional unexpected bump or rock or rut or whatever. But if your bike headshakes over normally encountered obstacles, look to find the problem, not cover it up with a damper.
Just my thoughts and opinions...TW

[jmiakaike]

Originally posted by FFRacing11x
raising the frontend does a few things...
increases rake
increases trail
puts more weight on the rear
increases swingarm angle
forks will have more stiction

lengthening the wb by adding links
steepens rake
decreases trail
puts more wt on the front
increases the leverage ratio on the rear shock

One of the most common reasons for headshake is not having the fr and rr suspension "balanced" ie. front too stiff and rear too soft etc.
2nd reason is having the steering head bearings misadjusted or they are worn out.
Like I said in a previous post, a damper will not cure chronic headshake. It is there to help out for the occasional unexpected bump or rock or rut or whatever. But if your bike headshakes over normally encountered obstacles, look to find the problem, not cover it up with a damper.
Just my thoughts and opinions...TW

i agree with ffr.. especially the balance part.

just my .02 cents..

james

[JohnLorenz]

correct Bill its not the same and we will ban that guy LOL