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Discussion Starter · #1 ·
So I have an 06 ninja 650r. I notice I have a high speed front end wobble, particularly at 90+ going around turns and about 110+ on straights. If I apply pressure with both hands on handlebars it seems to alleviate the issue some. I originally noticed that my front tire was choppy so I replaced it and no change. The fork seals don't seem to be leaking either and everything seems to be tight. I do feel that my forks may be a little higher up the triples then stock, I have had them off. Also have had rear tire off and replaced sprockets, the rear seems to be lined up by the marks on the swingarm. Aside from tires I do all the work on it. Please help diagnose this issue.

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sickboy
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First thing that came to mind was forks to high in triples (before I even read that) so I would guess either that or maybe even bad steering stem bearings?
Exactly how high in the triples are the forks? If they are over 5mm above the top I would say thats your problem.
 

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isit a weave orra distinct wobble/shimmying at high speed?
 

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If I apply pressure with both hands on handlebars it seems to alleviate the issue some.
DO NOT DO NOT DO NOT do this. Ever. I've known several people who went down trying to get a little more speed by shoving forward on the bars. A wobble is from an imbalance of force, or more specifically a lack of damping causing it to "hunt" for equilibrium i.e wander back and forth. Shoving forward temporarily masks this but the root imbalance is still there, and with more speed will gain strength. At some point it will overpower your shove, rip the handlebar out of your hand, possibly break your wrists, and go into a full blown tank slapper. You have 600+lbs going 100mph, there's a lot of energy at play here and it's much stronger than you are.

If you get high speed wobble the correct thing to do is keep a light grip on the bars, roll off the gas, and smoothly apply the rear brake only until the wobble subsides. Jamming on the front brake can upset the barely-in-check oscillations and result in a tank slapper as well.

If you've ruled out cupped or worn tires, the next most common issue is loose or worn head bearings. The general test is to elevate the front wheel off the ground, put the handlebars center, and gently nudge them until they fall to one side. If they bounce off the stop, it's too loose. There's two castellated nuts under the top clamp. The top is a jam nut, the lower sets the tension. Use a flat screwdriver and a hammer to tap a little more tension on. If you develop a low-speed weave, like the bike doesn't want to hold a straight line, you got them too tight. Since your bike is fairly new I doubt they would be worn out, unless you wheelie and have hard landings a lot which can notch the races.
 

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I've heard of fork fluid causing this sort of thing. However I messed up when filling one of my forks and ended up guesstimating it. I also have never had an issue after coming down from a wheelie or at speeds of 100+
 

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Once You Go Italian...
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DO NOT DO NOT DO NOT do this. Ever. I've known several people who went down trying to get a little more speed by shoving forward on the bars. A wobble is from an imbalance of force, or more specifically a lack of damping causing it to "hunt" for equilibrium i.e wander back and forth. Shoving forward temporarily masks this but the root imbalance is still there, and with more speed will gain strength. At some point it will overpower your shove, rip the handlebar out of your hand, possibly break your wrists, and go into a full blown tank slapper. You have 600+lbs going 100mph, there's a lot of energy at play here and it's much stronger than you are.

If you get high speed wobble the correct thing to do is keep a light grip on the bars, roll off the gas, and smoothly apply the rear brake only until the wobble subsides. Jamming on the front brake can upset the barely-in-check oscillations and result in a tank slapper as well.

If you've ruled out cupped or worn tires, the next most common issue is loose or worn head bearings. The general test is to elevate the front wheel off the ground, put the handlebars center, and gently nudge them until they fall to one side. If they bounce off the stop, it's too loose. There's two castellated nuts under the top clamp. The top is a jam nut, the lower sets the tension. Use a flat screwdriver and a hammer to tap a little more tension on. If you develop a low-speed weave, like the bike doesn't want to hold a straight line, you got them too tight. Since your bike is fairly new I doubt they would be worn out, unless you wheelie and have hard landings a lot which can notch the races.
This is it exactly. Thanks for explaining it to him.

Watch the Twist of the Wrist II DVD. Exact opposite of what you should do.


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jamal avatar #1
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DO NOT DO NOT DO NOT do this. Ever. I've known several people who went down trying to get a little more speed by shoving forward on the bars. A wobble is from an imbalance of force, or more specifically a lack of damping causing it to "hunt" for equilibrium i.e wander back and forth. Shoving forward temporarily masks this but the root imbalance is still there, and with more speed will gain strength. At some point it will overpower your shove, rip the handlebar out of your hand, possibly break your wrists, and go into a full blown tank slapper. You have 600+lbs going 100mph, there's a lot of energy at play here and it's much stronger than you are.

If you get high speed wobble the correct thing to do is keep a light grip on the bars, roll off the gas, and smoothly apply the rear brake only until the wobble subsides. Jamming on the front brake can upset the barely-in-check oscillations and result in a tank slapper as well.

If you've ruled out cupped or worn tires, the next most common issue is loose or worn head bearings. The general test is to elevate the front wheel off the ground, put the handlebars center, and gently nudge them until they fall to one side. If they bounce off the stop, it's too loose. There's two castellated nuts under the top clamp. The top is a jam nut, the lower sets the tension. Use a flat screwdriver and a hammer to tap a little more tension on. If you develop a low-speed weave, like the bike doesn't want to hold a straight line, you got them too tight. Since your bike is fairly new I doubt they would be worn out, unless you wheelie and have hard landings a lot which can notch the races.
+rep
 
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Watch the world burn
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Kawi manual states to raise forks over triples by 10mm.
 

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Discussion Starter · #11 ·
ok so i got some time to mess with it today and lowered the triples and did my best to make sure they r at even height. road test and still the same thing. now i am going to look into the stem bearings. also thank you everyone for your input.:cfrocks:
 

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Discussion Starter · #12 ·

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The height in the triples shouldn't make a tremendous difference. I'd check your stem bearings, tighten them a bit to see if that helps. There is a special tool for the castle nuts but a flathead screwdriver and hammer works fine to tap the bottom one a little tighter. Just a tap or two...don't go nuts. Over tightening them causes low speed weave.
 

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Is your front tire on the right way? When I had new rubbers put on they put the front tire on facing the wrong way, gave it a bit of a high speed wobble. I put it on the right way when I redid my front end and had no problems after that.
 

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Discussion Starter · #15 ·
so i tightened up the front end like it has been sugg and it seems to have def helped. I didnt test it out too long cuz i didnt want sum crazy shit to happin but the wobble in the turns seem to have cleared up and in the straights it isnt till about 125.
 

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Stem tension is kind of a trial and error thing. There is a torque spec in the manual, but you usually can't set this without a special tool, and even then I've improved stability by playing around with it...usually a little tighter than the book suggests.

I imagine 125 has to be about the top end for a 650 anyway? A stripped, unfaired bike is an aerodynamic disaster, so some slight instability at higher speeds is kind of to be expected.
 

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Discussion Starter · #17 ·
ive had up to 145 faired. about 130 sumthin unfaired. 128 different gearing. but it only seems to do it around top speed and if its not a fairly smooth road, so alittle more adjustment and it should be good
 

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You can buy a size 30something socket then take a cutoff to it and have the socket to torque it to spec. If you can get your front end off the ground you can check the condition of your bearings; just turn the bars looking for notchiness.
 

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A little bit of a "squirrely" feeling at top speed on not smooth roads is not at all unusual and I would not consider it to mean something is wrong with the bike. 650's have suspensions designed for commuters and general street riding, not a nine tenths pace. At top speed it's undersprung and underdamped to cope with the forces involved.

Cranking up the preload on the rear shock might help. At high speed wind drag on the front of the bike makes it squat in the back and lightens the front wheel which can cause wiggles. Minimizing this with more preload can sometimes help. Granted at the cost of ride quality at lower speeds so pick what's more important to you.
 
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