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Wobble at 105MPH, Why?


act1976

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A buddy and I were riding home together on Hwy 820 on Thursday and I noticed a wobble at 105mph. I rolled off the throttle and it smoothed back out, but rolled into 103-105 and it began again. Anyone know why?
 
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Several factors in play.. windscreen, stock hand guards, tires/tire pressure, suspension, and rider input to name a few... I personally have never experienced a "wobble" all the way up to 115mph with SHAD cases on... 125mph with them off.
 
Do a search on the forum.. there has been a lot of discussion on possible remedies.

'15 FJ-09 w/ lots of extras...

Fayetteville, GA, USA

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A buddy and I were riding home together on Hwy 820 on Thursday and I noticed a wobble at 105mph.  

 
 
 
 
 
Is this bike new to you? have you had it up to 105 before? have you ever had any sort of wobble before?
 
 
as @duhs10 stated, many factors can contribute to a wobble, this bike is a little taller and not quite as aerodynamic as a naked or sport bike. 
 
When riding at 105 were you accelerating or maintaining a set speed?  were you tucked to the tank or sitting upright?  Do you have luggage? top box or side bags?  Stock suspension? fork caps flush with top clamp or raised?  Sag set with proper spring rate?  The reason I mention suspension, when you are accelerating, your rear end squats and the front end gets lighter.
 
 
 
Since you were riding 105, I assume you weren't on an interstate or highway with other cars or large trucks creating turbulent air?
 
 
I'm going to assume that the chain is ok condition, tires are good and wheels are balanced.
 
 

***2015 Candy Red FJ-09***

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Yes I bought it about three weeks ago; Nope first time; No that is why I was a bit freaked out. We got up to speed and I maintained it; I was slouched more upright; no luggage of cases. Stock suspension; fork caps down to two threads above flush; rebound needs to be adjusted. We were on a Hwy in the left lane very little traffic at 12:40am. Chain is new and about 40-60 miles before tension adjustment is needed. Like I said it was bought 3 weeks ago and I have not curbed it or bounced it off something to take the alignment or balance out.
 
Thank you all!
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This is an old video, but physics don't change and it's still an entertaining watch in a quaint way.
 
In short, it can be cause by aerodynamics, weight balance, and tire design.  Try leaning forward...but also, maybe don't go 105mph...
 
[video src=https://www.youtube.com/watch?v=fvsDIq3WwVA]
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but also, maybe don't go 105mph...
 
I tried putting "FJ-09" and "maybe don't go 105mph" into Google Translate, and it came back with "Does Not Compute".  8-)
 
 

***2015 Candy Red FJ-09***

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  • 2 weeks later...
Have to say I have the same issue and have since I got the bike 6 months ago. My understanding is the suspension is set standard for smaller lighter riders. I am around 220 lbs with gear, 5-11 tall and still have factory settings. Done around 5,000 miles and am eagerly watching this thread to see the best way to remedy this.
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Have to say I have the same issue and have since I got the bike 6 months ago. My understanding is the suspension is set standard for smaller lighter riders. I am around 220 lbs with gear, 5-11 tall and still have factory settings. Done around 5,000 miles and am eagerly watching this thread to see the best way to remedy this.
I'm 280 lbs, 6.2 tall...  No wobble
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A buddy and I were riding home together on Hwy 820 on Thursday and I noticed a wobble at 105mph. I rolled off the throttle and it smoothed back out, but rolled into 103-105 and it began again. Anyone know why?
You’re holding onto the bars too tightly.  Relax your grip on the bars, arms slightly bent instead of rigid and your problem will disappear.  This has been discussed at length in a number of threads previously.  Many an armchair physicist have postulated all kinds of questionable mechanical theories and related expensive solutions.  This armchair scientists experimentally proven experience is that a loose, flexible grip on the bars combined with stock suspension adjusted for my weight allows me to ride any speed that the Tracer is capable of, without wobble. 
https://fj-09.org/post/43642/thread
 
Just yesterday I was riding a “private test track” in Northern Sweden with my semi-rigid Yamaha panniers fitted.  The “track” surface had been badly affected by winter frost heave and was bumpy and rutted.  At times I was doing up to 200 km/h (that’s 124 mph in old money); no wobble.
 
CS
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All of the above can be factors.
 
My only experience with this is the occasional high speed weave when the front end gets light. It's a rare thing in my case and even less so once my bike was properly sprung. Yamaha didn't increase the wheelbase on the GT by 2.5 inches for nothing, that is YOOGE, and IMO and acknowledgment that they know the bike is prone to it.
 
Assuming your bike has no maintenance issues and that is what is happening some things to consider:
 
Put massive amounts of farkles on the front of the bike. This seems to work for many here smiley.png
 
Check your grip. Aeros are difficult to mod beyond removing/changing hand guards, experimenting with the screen. Get the bike sprung for your weight and typical loading conditions. Raise the forks (you've done this). Check the steering head. Add a link or two to the chain.
 
Personally haven't done most of the these things other than dumping handguards, raising forks, and proper suspension but others have reported positive results.
 
 
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