KX125 head shaker

[ragingbull]

My boy has jumped up to a 125 and have him riding a 2001 KX125. The problem is the bike likes to easily go into a head shake. Put the settings all back to stock and have the recommended 100mm or rear sag and no help. Had a friend of mine ride the bike that is close in weight (135) and he seems to think the bike is a bit harsh over the small stuff. He felt this may have something to do with the problem and also felt as the bike was very twitchy over the higher speed smaller bumps but seemed to work well over the bigger stuff and jumps. Any recommendations or things I should look into, let me know...

 

[marcusgunby]

At 135lb he could do with softer springs at the least, probably also softer valving is needed, first you can lower the forks in the triple clamps 5mm and that should help alot.

 

[WWR]

Rebound set way too stiff? This could definately do it. Maybe someone seriously screwed with the valving, and the stock settings wont work. And like Markus says, see if the forks are set right in the Triples. I think the stock setting is to have only the fork caps extend above the top triple with no anodized fork portion showing.

Markus, wouldn't the springs being too stiff in the front cause more of a turning problem and less of a headshake problem?

In any case, check your sag settings. These will also tell you if the springs are too stiff. You never know, the previous owner may have mix-n-matched some suspension parts and you have no idea what is there.

 

[marcusgunby]

you can get headshake with many problems with suspension-too stiff at front and also too soft-reb too slow on front will cause it as well-02 kxs dont normally shake much so its got to be something out the ordinary.

 

[ragingbull]

Went through the front forks this past winter and they looked as if they have never been opened up but for sure could be wrong. Also, I have already dropped the forks down about 5mm in the triple clamp and this seem to help a bit. Now, are you saying that possibly my rebound is set to slow and the setting screw needs to be turned out??? Let me know as I wll try this next. As far as springs are concerned the factory springs (if this is what it still has) from what I have read are for a 145 pound rider. So my rider at 135 would be to light and the springs would be to stiff for him and this could be the reason for the head shake??? THANX MUCH for all of the input...

 

[WWR]

If the factory springs are for a 145 pound rider, they should be fine.

If your fork rebound is set too stiff (too far in), the forks "pack" over the higher speed bumps and ride lower in the stroke, giving you much the same effect as if the forks were raised in the triples. Where is your rebound clicker setting at? They KYB's on my '97 YZ run best at around 10-12 clicks out. Anything stiffer than that and she gets real twitchy over the choppy stuff as speed.

 

[marcusgunby]

Also most springs on 125 are for heavier riders than you expect, im 170lb expert and have gone to lighter springs on my recent 125s.

 

[ragingbull]

Ok my friends I thank you much for all of the info. I have backed off the rebound screw 2 turns from the factory 14 out to 16 out and hopefully will be able to give it a try soon to see if it helps. Again thanks much for the info...