Decelerating headshake

[cfar]

Morning all,
 
I've searched on the forums and elsewhere looking for a good solution and have come to no resolution.
 
The high speed wobble exists on my '17 09 but that oddity aside, I'm more baffled by recently noticing a decelerating headshake.  Mind you, its not a full on tank slapper but concerning none the less.
 
I don't typically accelerate hard in the mornings (or at all really) when its dark however this morning I had an opportunity and ran it up close to redline in 2nd gear.  When I let off, I noticed some headshake.  I didn't lift the front wheel and had my weight forward.
 
I'm 6'4", 225 with all my gear on, have a Givi screen all the way up with a deflector on top of it.  Shad top and side cases.  I don't remember my exact settings on the suspension but the rear is actually set pretty "soft" even though it feels firmer than the front which is about 3/4 way through the preload and about 2 clicks from full in on rebound.
 
Any ideas other than headbearing?
 
Thanks,
Chris

[norcal616]

quite a few of us have dropped the
"triple tree" bout 15-17mm from fork top, if you have not done so...

[cfar]

Any good results from more conventional tuning? If so stiffer better or softer?
 
I forgot to mention there was a small amount of what looked like axle grease down on the left side of the front axle yesterday that I wiped off.  I'd say a little less than a fingertips worth.
 
One more thing that I always associated with the pads (shifting back and forth in the caliper) is that if I apply the front brake while going backwards, I get a click.  When I go forward again I get another click but it stays quiet as long I always go forward.

[dbeau]

No way around it as far as I can tell. I think it is just a product of the bike's geometry. I've upgraded my suspension forks and rear and set up properly and still get a slight decel wiggle. Upgrading the suspension completely cured the high speed wobble though. You have to take the good with the bad on this bike.

[cfar]

Right on thanks guys

[angrygirafe]

Try it without luggage. If I’ve got cases on my bike and let go of the bars when coming up to a light, there’s a slight shake. Doesn’t happen without the cases.

[skipperT]

Any good results from more conventional tuning? If so stiffer better or softer? 
I forgot to mention there was a small amount of what looked like axle grease down on the left side of the front axle yesterday that I wiped off.  I'd say a little less than a fingertips worth.
 
One more thing that I always associated with the pads (shifting back and forth in the caliper) is that if I apply the front brake while going backwards, I get a click.  When I go forward again I get another click but it stays quiet as long I always go forward.

 
Grease on axle - normal.
 
“Click” from front brake area - also normal, it’s the floating rotors moving slightly and/or the inner fork tubes shifting slightly within the outer tubes.
 
If you see oil running down the back of the lower fork tube leg then you have a leaky seal.
 
RE: headshake, as others have mentioned it’s fairly typical. Bump the rear preload, try without the bags, raise the forks into the upper clamp a bit are all good suggestions.
 
Also consider: worn or cupped tires, low pressures, and wind resistance from the hand guards. Do NOT underestimate cupped tires, they really do affect it!
 
If you really want to solve it: replace the steering bearings with tapered roller bearings from Allballs or install a steering damper.
 
-Skip
 

[empire00]

Also consider: worn or cupped tires, low pressures, and wind resistance from the hand guards. Do NOT underestimate cupped tires, they really do affect it! 
If you really want to solve it: replace the steering bearings with tapered roller bearings from Allballs or install a steering damper.
 
-Skip

Most people that are having the "normal" headshake issues are having it at speed. I think cupped tires are the likely suspect here. That is the only thing that has ever caused me any deceleration headshake on any bike I have owned. My last case the tires looked good and were balanced correctly but they had some light cupping. New front tire and everything cleared right up.
 

[adamr]

“Click” from front brake area - also normal, it’s the floating rotors moving slightly and/or the inner fork tubes shifting slightly within the outer tubes.

 
 
 
 
 
That click is actually the pads moving in the spring clips that hold them.
 

[johnakay]

my understanding on this is that the hand guards are the culprit.
read that some recon its cause the the whirling effect on the guards.
not ridden my bike as yet.
to be honest I dont like the look of the H/guards looks big and bulky so will remove later.
.
 
 

[cfar]

Thanks guys. Tires are only about 1500 miles old (as is the bike) and were always inflated to favor spec. I haven't seen any cupping, just the aforementioned grease on the axle.
 
 
I could see how it might be an aero issue at high speed but say it by caveat, I am no aerodynamicist. That said, here is my layman theory.
 
If there is any imbalance from the air pressure on one handguard and it is enough to push the bar to one side at high speed, the effect would be to reduce the pressure on that handguard because it is being pushed more parallel to the wind. This push would then pull the opposite handguard into the wind at a higher angle increasing the pressure there which then would push it back the other way and the wobble begins.
 
I'll take my guard off and test it out.

[betoney]

If you haven’t already done so, raise the forks in the clamps a few millimeters, this puts a slight forward weight bias on the bike.
The FJ and FZ (I haven’t ridden an XSR or Tracer yet) have a flighty feel to the front end when accelerating, add in a soft rear shock and you could definitely feel some flutter or shake.
I don’t have oem suspension or use the oem handguards.

[Guest]

Head shake has been narrowed to the rear wheel alignment with the rear axle notches not correlating left and right side. Do as manual alignment with the front wheel. My bike does not exhibit the shake.

[BBB]

2 minutes ago, fz1rider said:

Head shake has been narrowed to the rear wheel alignment with the rear axle notches not correlating left and right side. Do as manual alignment with the front wheel. My bike does not exhibit the shake.

I’m sure this could contribute, but other factors are definitely also in play.

[Tripletrouble]

I changed my tyres to pilots. This reduced that 70 mph ish light bar weave feeling, and no head shake on de cel . I found original tyres felt a bit hard after a short time, whilst the michelins still feel so much nicer, more pliable and grippy.  Raising forks in trees, could put more weight on bars, good in corners and accelerating, but could ? make it worse otherwise, as your sharpening up the rake, making it twitcher. Think of a cruiser having slack rake, more stable but slower steering.  As you've mentioned, it's generally a symptom of worn head bearings. Changing to tapered. Not sure, did this on sports bike, but, they needed a bit more attention, as they wear they loosen up and need to be adjusted. Other than that, off to the doctors and check your elbow joints ! 

Edited February 2, 2019 by Tripletrouble