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kakusaizou

Head shake

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kakusaizou
Just had a slight but heart-sinking shake at the bars when I hit a small bump merging left at 80mph. This was just after I did a chain adjustment. Now every time I flick the bars left or right above 60mph there is slight shake until it stabilizes itself. Could a tight chain cause this?

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rmdet
Did you check the alignment marks on the rear, and if so, are they at the same mark?
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cndnmax
My money is on alignment also.

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rowdy
Oh yea! It's called "speed wobble" or sometimes, more ominously "death wobble" and I've had it on my bicycle descending a canyon at 55 mph (I almost crapped my shorts). There are many factors that can create it, and sometimes it takes a (bad) combination of things to create it. Here's some good info from wikipedia. I too would check closely you rear wheel alignment, as well as your headset tension. I think the short wheelbase on our bikes could make it easier to have this happen when something isn't quite right. I would also recheck the chain tension, but I doubt it is the cause.
Also, wheels out of balance can cause it, and even having a death grip on the bars can contribute to it.
 

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howworkclutch
The chain may be too tight. I had a Honda cb450 that would scare the pants off ya if the chain was too tight.
 
My Harley developed a wiggle at 90mph. I suspect the guy who changed my rear tire over-tightened the belt tensioner. Since I rarely went faster than 80 I didn't worry about it. I changed the belt before a long run and the problem went away.
 
 

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Beemer
It's probably the alignment but a fork brace is nice to help eliminate the "Death Wobble". Try that process of elimination. Can't seem to find a fork brace for our bike, poop! Has anyone seen any?

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batscat
Damn if you don't know what you are doing take it to a shop pay $20 to get chain done right before you kill yourself.

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avanti
I always (and suggest) taking a picture of the alignment marks on each side of the bike, with a precisely centered camera placement, while it is working right (assumed) and BEFORE adjusting anything! The reasons I say this are: 1) I agree with the others who suggest a chain adjustment problem (especially since the issue seemed to have just appear post-adj), and 2) because the alignment marks are often not exactly perfectly aligned from side to side. Regarding the latter, my 07 has one exactly "on the mark" (exactly centered) on one side but just "early" on the corresponding mark on the other side. The difference is very slight, and might, just might not matter but since the bike works fine as is, that's exactly the relationship between the two marks I'll reproduce when doing my first adjustment. All the BEST!!!

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kakusaizou
Interesting, the right plate moved and I had to adjust it AFTER lining both plates and torqing the axle nut. Should the right plate sit flush to the swing arm after torquing the nut?

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bmwpowere36m3
Interesting, the right plate moved and I had to adjust it AFTER lining both plates and torqing the axle nut. Should the right plate sit flush to the swing arm after torquing the nut?
Yes, both chain adjuster blocks should be flush with the swingarm.  Before tightening the axle nut, I insure the rear wheel is fully pushed forward.  What I do is insert a small wrench between two teeth of the rear sprocket and rotate the rear wheel till the wrench is "sandwiched" between the sprocket and chain… Don't go crazy, you'll feel additional resistance when turning the rear wheel as the wrench gets sandwiched. 
This puts tension on the rear wheel pushing it, the chain blocks and the axle forward.  Tighten axle nut and then spin the rear wheel the opposite way to release the wrench.
 
Like this:
 
IMG_0483.jpg
 
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kakusaizou
Whipped out the chain alignment tool and it checks out. Loosened chain within spec.
 
x6Pu4vD.jpg
 
Head shake still there. Now I'm curious if it's just the characteristic of the bike. I'd like to know if anyone else experiences it by wiggling their bars left and right at about 60mph+. It's not an all out tank slapper but still doesn't feel normal.
 
 

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cndnmax
Head shake still there. Now I'm curious if it's just the characteristic of the bike. I'd like to know if anyone else experiences it by wiggling their bars left and right at about 60mph+. It's not an all out tank slapper but still doesn't feel normal. 


Not sure I understand. If you wiggle the bars your going to make the bike wiggle too.... Steering gets more sensitive with speed.

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rowdy
I took mine out today and pushed the bars a bunch of times to start an oscillation. The bars oscillated for a second then quickly straightened out.
I tried this several times at various speeds between 60 and 80. Also on the ride, I happened to be in a headwind and the vortex behind some vehicles seemed almost like it could have put me into speed wobble. I wasn't brave enough to push the bars while that was happening. ;)
So far, I have never had it happen to me.
 

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rowdy
Not sure I understand. If you wiggle the bars your going to make the bike wiggle too.... Steering gets more sensitive with speed.
If you have the right conditions to start speed wooble, when you wiggle the bars they can go into a feedback loop that will keep them wiggling, even though you stopped wiggling them.  See the wikipedia link I put up earlier in this thread. 

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kakusaizou
I took mine out today and pushed the bars a bunch of times to start an oscillation. The bars oscillated for a second then quickly straightened out. I tried this several times at various speeds between 60 and 80. Also on the ride, I happened to be in a headwind and the vortex behind some vehicles seemed almost like it could have put me into speed wobble. I wasn't brave enough to push the bars while that was happening. ;)
So far, I have never had it happen to me.

That's what I'm talking about. Seems prone to shaking. I stumbled upon it like I described it in the first post.  
I've own sport bikes that never exhibited this kind of shake and am curious to know if I have a defective bike or if this is common amongst FZ-07s.
 

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