Headshake



7 replies to this topic
  • jaybird67k

Posted February 17, 2001 - 03:18 AM

#1

Head shake is very very scary especially topped out in 5th gear warming up the beast, I dont care for this out of controll feeling. Last week at the track approaching a 60' table top there was some little bumps a short ways from the take off ramp that was causing head shake, luckily It ironed out before hitting the jump. I know about the dampners on the market but am reluctant to go that route without first trying to adjust my forks first.
I am 165lbs and have the clickers backed out top and bottom 2 clicks, which seems fine for jumps and landings. Is this a rebound problem and if so should I give it less rebound to soak up the small stuff with a more delayed return ?
If I have to buy a dampner I will but there are to many MX'rs not using them so there has to be a solution.
Thanks in advance guy's.


Jason
Beaumont. TX

50 degrees here......damn its cold !!!LOL

  • vznx1w

Posted February 17, 2001 - 04:45 AM

#2

Jaybird,

Your YZF shouldn't headshake if properly adjusted. Before changing the suspension make sure the steering head bearings are properly adjusted.

To do this put the bike on a stand with the front wheel off the ground. Hold the wheel straight ahead and gently push to one side. The forks should gradually fall to the steering stops. If the clunk or bang into the stops tighten up the steering head bearing adjustment until the movement is slow and fluid.

Other adjustments:
1. More rear sag
2. If the fork tops aren't already flush with the top triple clamp, do this so that the front end rides as high as possible.
3. More front compression
4. Less front rebound
5. More rear rebound

All four of the above adjustments are aimed at keeping the backend down and the frontend up as you go through the stutter bumps. This will keep more rake/trail in the frontend a provide more stability.

  • MikeOK

Posted February 17, 2001 - 05:52 AM

#3

Yep, you should never get head shake on a 426. Topped out in 5th on a track? A 60' table top? You were probably lucky it slowed you down, topped out in 5th you should be able to clear about 4 60' tabletops... A 60 footer should need 2nd, no more than 3rd gear if you run stock sprockets...

  • forloop

Posted February 17, 2001 - 07:35 AM

#4

MikeOK:

In jaybird67k's defense he did say while warming it up he was in 5th gear.

But, the first time I read it I got the same impression as you. I had thoughts of Robbie Knievel jumping the canyon on a 426.

The sound a lone would be too cool :)


------------------
Rick
01 YZ426F #85 Vet C

[This message has been edited by forloop (edited 02-17-2001).]

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  • motoman393

Posted February 17, 2001 - 07:39 AM

#5

Jason,

I am about your same weight also and ride MX too and sometimes experience the front end "wobbling around" at times (only at fast paced track ...4th gear) I talked to John Mitchell at J&M Racing and he said that the 01' 426 suspension is the best ever on a production bike and is so close to being perfect...he also stated that someone in the 150-180lb range will not need to revalve, but just fine tune the clickers.

He also said after awhile (a year or so) my fork springs will start to "lose their springiness" and recommends the .47 kg/mm for the 01' YZ426!

Maybe we can hook up and ride sometime? We are riding tomorrow, but arent sure where yet? Have you ridden at Super Dave's Flying motoworld? They have 2 MX tracks and a 20 mile Haresrcamble course...I've never been there just wondering if you have since it is closer your way! Anyway I gotta go watch Ricky Carmichael whoop up on Mc Grath in the SX series on espn2! Later,

Garrett

------------------
I get my kicks on a 2001' YZ426!
Friendswood, TX

  • jaybird67k

Posted February 18, 2001 - 04:13 AM

#6

Yes in my defense I was in 3rd gear over the 60 footer Mike OK. I like to warm it up with a good 5th gear wheelie. I adjusted the rebound 2 clicks stiffer to try to keep the front wheel down but this just added to the problem plus made it springy feeling. I went back to the original setting and backed it off 2 clicks which seem to help a little.
I never noticed this problem until a week ago after a terrible crash when I made pretzles out of my bars( I got very lucky)
I put new bars on and readjusted the alignment, then when I rode after a few normal jumps it tweaked the steering again....Slightly. I wonder if this is part of the headshake problem ?
I appreciate all the info.


Jason

Beamont,Tx.

  • dirtdad

Posted February 18, 2001 - 04:53 AM

#7

I think you just answered your own question.

  • Boit

Posted February 18, 2001 - 10:14 PM

#8

Besides the crash damage.....forks riding too low in the stroke will create headshake. This is usually cured by stiffer springs....or by sliding the tubes DOWN into the triple trees. However, it can be a trade off. Cornering prowess might, and probably will, be compromised.

Jeremy Wilkey has a suspension forum on WWW.dirtrider.net and will answer questions for free. You have nothing to lose by asking him.

[This message has been edited by Boit (edited 02-19-2001).]





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