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Discussion Starter · #1 ·
Hello all,

I'm having some trouble with a front end wobble/handlebar shake/shimmy. It started about 6 months ago and has gotten progressively worse since. At first it was a mild shaking of the handlebars when decelerating without holding the handlebars (not braking) from ~48-43mph. I took it to a shop who told me they were theoretically unable to replicate the wobble, but checked the balance on the front tire (normal) and greased the steering bearings. The bike wobbled exactly the same after I got it back.

The wobble has gotten progressively more violent, and it's lasting longer - 52-32mph. I can strong-arm it into keeping the front wheel straight, but it's getting harder to do that, and the bike is starting to wobble in corners now. I have had 2 other people of different size and stature ride it, and they can both get it to wobble the same way I can.

I took it in to a different shop, who also told me that they can't make it wobble. They told me one fork seal was leaking, which I had them fix, and while they had everything apart, I had them upgrade the bearings to the tapered ones, just to rule that out. The bike has ~20,000 miles on it at the moment.

When I got the bike back from this shop, it wobbled exactly the same. It seems to only occur under deceleration. Braking does not add to the severity of the wobble. For fun, we tried riding it with a passenger, which significantly decreased the wobble, but didn't entirely resolve it. After noting that, we tried adjusting the rear suspension. It had been set on the second setting, so we increased it all the way to position 5, which helped a good bit, but the bike was still wobbling. Riding one up and sitting on the passenger seat itself, with the shock at position 5, almost entirely removed any trace of the wobble/handlebar shimmy. We then decreased it all the way to position 1, which made the wobble worse than position 2.

I have a suspicion that the rear suspension adjustments are just masking the original problem, but I'm at a loss of what to check next. I don't see any uneven wearing of tires, front forks have been loosened in the triple and re-torqued, rear wheel is running true, etc. Anyone have any suggestions?
 

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I immediately thought BEARING....until I read you changed that too. 馃

The only other thing I could think of is front wheel balance? But you had that checked too!

Weird! 馃馃馃
 

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Discussion Starter · #3 ·
I immediately thought BEARING....until I read you changed that too. 馃

The only other thing I could think of is front wheel balance? But you had that checked too!

Weird! 馃馃馃
And tire pressure normal, etc. Ugh, frustrating.
 

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Have you had the front tire checked for cupping? I know you said you saw no unusual wear, but cupping is sometimes easy to miss. I had a horrible front-end wobble. I changed the steering bearings, had my fork seals rebuilt, and it seemed to be worse and the vibration, even with the weighted bar ends, was making my fingers numb. When I took it in to get a new rear tire, my friend, who owns the shop, pointed out that the front tire was cupped. Once I replaced that, all was right with the world.
 

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Discussion Starter · #5 ·
Have you had the front tire checked for cupping? I know you said you saw no unusual wear, but cupping is sometimes easy to miss. I had a horrible front-end wobble. I changed the steering bearings, had my fork seals rebuilt, and it seemed to be worse and the vibration, even with the weighted bar ends, was making my fingers numb. When I took it in to get a new rear tire, my friend, who owns the shop, pointed out that the front tire was cupped. Once I replaced that, all was right with the world.
I have not, but it sounds like that's my next item to check. Thank you!
 

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Interesting story. I have a friend who has a N300 as well, and has the same story. We checked the head bearing, it was good. Changed from stock to real tires, still happens, but less so. Pressures good too. Only happens in a similar speed range to yours, without holding the bars. Although her problem has not progressed worse and worse...

Good thinking on the fork mounts, that was gonna be my first suggestion after head bearings.

Sometimes poor enough suspension settings can cause this, but it shouldn't worsen over time...

My friend got her bike practically new, and it only developed her wobbling issue after a bad drop/low speed crash.

Have you hit any especially bad potholes? Id take a dial indicator to the front wheel, brake rotor, and it's more work, but you could roll the fork tubes across a piece of glass to confirm straightness.

I suspect on my friend's bike, some little part got tweaked a tiny bit, and causes the wobbling. Although I am hesitant to say the same about yours, since your condition is actively worsening.

Perhaps something is loosening on your bike? That's the only condition I can think of that would make it worse over time, besides tire wearing, but I would replace the tire anyway for good measure.

-Mike
 

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You have already tried most of what I was going to recommend...

I might double-check the rear wheel alignment, just for kicks.

What tire is on the front, and how old is it?

Kind of a long-shot, but have you checked the engine mounts? There isn't a lot of frame on the Ninja, and it is relying on the engine to hold things together firmly. Swingarm bushings might be another thing to check.
 

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I noticed a slight wobble when the front tire was worn. When I replaced it, the wobble went away. You may not have unusual wear, but you might have a normally worn, but worn out tire. I find 25,000+km on a tire is about as much as I'd want to have on a tire before I will replace it.
 
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