Bad Headshake at High Speeds


37 replies to this topic
  • TIG88

Posted June 14, 2009 - 01:24 PM

#1

Hey guys, the title says it all. Above say, roughly 50 mph or so, on any hard surface (road, dry field) I get a terrible headshake.

This isn't normal on a 1st gen 450f, right? On a soft surface, it wont do it. I find it pretty annoying that some of the guys I ride with, on CRF230's, will blow by me going through a long straight away if it hasn't rained in the past week.

Any other suspension tidbits you guys might wanna add would be wonderful. I admit, I know nothing about it. My bike's suspension was 'set up' for a guy just about my height and weight (thankfully), but that was for motocross. It has a little sticker with some of the settings on it.

  • grayracer513

Posted June 14, 2009 - 03:19 PM

#2

Are the forks pulled up?

Stock or offset clamps?

Does it shake from pure speed on a flat surface, or as a result of deflecting off a bump?

  • FinchFan194

Posted June 14, 2009 - 03:51 PM

#3

Lean back further.

  • mikedabike

Posted June 14, 2009 - 08:09 PM

#4

Bent wheel maybe? The front tire does not get enough traction on the soft terrain to make it shake. When you are on hard pack the tire has enough traction to transmit the shake up to the bars. I have a bike with a bent front wheel that does this.

  • TIG88

Posted June 15, 2009 - 11:10 AM

#5

Thanks for the replies guys. I took the wheel off and examined it, as near as I can tell, there is no bend in it. Seems to be round.

Forks are in the stock position. Not sure about the clamps, how do I tell?

It shakes from pure speed. Just cruising down a flat road will do it towards the top of 4th.

  • FinchFan194

Posted June 15, 2009 - 02:25 PM

#6

I know I didn't go in depth before about leaning back, but if you are trying to lean over the front of the bike you will get headshake I don't care what brand it is. Oh and your stock clamps are bare aluminum and are cast aluminum and have a textured finish.

As Grey stated your sag might be a problem too.

  • 642MX

Posted June 15, 2009 - 04:34 PM

#7

Mine did it a little before the revalve. I found that if I just lightly dragged the rear brake it would stop doing it (not sure why, but it worked). The revalve fixed all kinds of quirks the bike had. :thumbsup:

  • Diode663

Posted June 15, 2009 - 04:48 PM

#8

This is strange, I couldnt get my 04 to headshake if I tried. My 07 on the other hand keeps me pretty puckered.

  • Ogener

Posted June 15, 2009 - 04:57 PM

#9

My 05 had such bad headshake this last weekend I thought it was gonna take the bars out of my hands! But I believe it was more from the bumpy ground I was on when I was in 4th almost tapped out than anything wrong with the bike.

  • desert-rat660

Posted June 15, 2009 - 05:19 PM

#10

chek to see if u have any play in the steering tube bearings

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  • jcham33

Posted June 15, 2009 - 05:40 PM

#11

I had the same problem, it turned out that one of my forks was shot.

  • YamaLink

Posted June 16, 2009 - 05:28 AM

#12

Other option added to the list of sag, bad bearings, fork height, bent wheel, etc., is maybe your rebound is set too slow and it's packing at speed? Long shot but you may try a slightly faster fork rebound.

  • grayracer513

Posted June 16, 2009 - 06:12 AM

#13

Check the alignment of the rear wheel. Don't go by the marks on the swing arm, straight edge it from sprocket to sprocket.

http://www.thumperta...487#post5232487

  • MOTOPHILE

Posted June 16, 2009 - 06:27 AM

#14

but if you are trying to lean over the front of the bike you will get headshake I don't care what brand it is.


Huh??

Sounds like a suspension not set up correctly to me...

  • FinchFan194

Posted June 16, 2009 - 01:48 PM

#15

Huh??

Sounds like a suspension not set up correctly to me...


If you are leaning over the front of the bike with it pinned in 4th gear and not standing up leaning back then you are gonna get headshake. Ya less likely with the straightline stability of YZf's but he probably has a suspension issue too.

  • TIG88

Posted June 16, 2009 - 01:52 PM

#16

Alright guys, took her for a ride up the road just now. Tried dragging the back brake, and it didnt do any good. I have to go out to dinner tonight so I dont have too much time to play with it.

After a quick inspection, it appears my fork seals are leaking quite badly. I dont know how I could have missed this, but I'm pretty meticulous about things being clean. There was alot of oil on the bottom of the tubes.

The bearings. The wheel bearing check is a no brainer. How do I check the steering tube bearing? I suppose I could take it apart and see how she looks/feels, but if theres an easier way, I'm all ears.

The rear wheel alignment will be the first thing checked tomorrow when I will hopefully have more time.

The clamps are stock.

FWIW, the problem could have been existant the whole time, I had never really opened it up on dry ground. I live down a back road, and the road has recently been paved, so I'm pretty sure its not being caused by bumps. It feels like its gonna rip itself outa my hands. If I had to guesstimate, I'd say it starts at about 50-60mph.

I appreciate all the help guys.

  • MOTOPHILE

Posted June 16, 2009 - 05:22 PM

#17

After a quick inspection, it appears my fork seals are leaking quite badly.

How do I check the steering tube bearing?.


Well an empty/low fork oil level is probably causing your issue. New seals are cheap and not too bad to change. Use your old seals to drive in the new ones. Just be careful not to scratch anything. Check fork bushings while your in there. Lots of threads on here about how to in the suspension forum.

For the steering bearing, if you pull in the front brake and push bike forward and backward do you feel any play or notchiness in the steering tube? Also put bike on a stand with the front tire in the air and turn handlebars from stop to stop. You shouldn't have to push and they shouldnt just fall on there own either. Might as well grease it when you do the seals anyway. I bet it needs it. Sorry for lack of details, in a bit of a hurry. Good luck.

  • Diode663

Posted June 16, 2009 - 06:32 PM

#18

Before I replaced the seals I would try cleaning them out with a film negative and refiling them. If this cures the problem then you should be in good shape, if not then a seal change is in order and you should definately invest some time into the steering stem bearings.

  • MOTOPHILE

Posted June 17, 2009 - 04:44 AM

#19

If you are leaning over the front of the bike with it pinned in 4th gear and not standing up leaning back then you are gonna get headshake. Ya less likely with the straightline stability of YZf's but he probably has a suspension issue too.


Anybody else agree/disagree with this statement?

  • grayracer513

Posted June 17, 2009 - 08:09 AM

#20

If you are leaning over the front of the bike with it pinned in 4th gear and not standing up leaning back then you are gonna get headshake.


Anybody else disagree with this statement?

Yes..





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