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Discussion Starter · #1 ·
I have a regular Thrux and when I ride over 70 mph, my rear feels unstable. Especially if it is even a smidge windy outside.
I have never felt this problem with any of my other bikes, so it is kind of hard to explain.
It almost feels like something is loose and then I feel wobbly. Or if you ever ride on an asphalt street that has extensive repair and they seal up cracks with the black goopy crap. Then you ride through it and you can feel it is unstable. That is what it feels like.

So I went and make sure everything was tight and no obvious issues to this amateur grease monkey.

So I'm thinking maybe unbalanced tire or something? Or suspension issue? Right now it is set on the factory setting.

So I'm not sure what is up. Anyone else have this problem or any advice?
 

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Try softer suspension then harder, what tyre pressure are you at? An imbalance would feel lumpy not necessarily squirrely. Perhaps it's just a new bike getting used to.
 

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Discussion Starter · #3 ·
Try softer suspension then harder, what tyre pressure are you at? An imbalance would feel lumpy not necessarily squirrely. Perhaps it's just a new bike getting used to.
I think stock is the softest? (Someone correct me if I'm wrong).
Tire pressures were good.
It's just strange, at highway speeds i feel like the bike is swaying under me. Really strange, and doesn't feel normal. There was one point on the freeway I slowed down to 60 and took the enxt exit to check things out, it was that noticeable.
Doing first service when I get back into town in two weeks and will have them check it out.
 

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Check out the front end as well, sometimes a problem at the front can feel like its at the rear.....Make sure everything is tight around the forks and wheel and the front tyre pressure is correct..
 

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Trevor....I have identical Thruxton.......No issue here and I have touched 105 indicated briefly on the highway. I am on delivered rear shock setting. #1 position. Everything feels fine. I am at 735 or so miles. I have had other bikes where at time the rear felt a little weird but it ended up being tire pressure on all occasions. Usually just down a little. So that would have been my first guess. Keep us (me) posted as to what you find. Chip
 

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Discussion Starter · #6 ·
Will do, I will re-check tire pressure with another meter when I get back into town. Won't be riding till June :-(
 

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Discussion Starter · #10 ·
Trevor....I have identical Thruxton.......No issue here and I have touched 105 indicated briefly on the highway. I am on delivered rear shock setting. #1 position. Everything feels fine. I am at 735 or so miles. I have had other bikes where at time the rear felt a little weird but it ended up being tire pressure on all occasions. Usually just down a little. So that would have been my first guess. Keep us (me) posted as to what you find. Chip

Good to know then. I mean it could be getting use to a new bike, but it just seems so unstable…


Have you fitted stuff like a screen or panniers? they can often mess things up.

Nothing aftermarket yet.


I'd have bet on front tyre pressure but you're already going to check those.
Maybe I need to pick a nice digital TP gauge instead of the cheapy .97 cent ones. Atleast I will have a better peace of mind and better idea when I go into the dealership.

Got all this beautiful weather and I'm not even home to enjoy it!
 

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Unless I miss my guess looking at the photos, the factory has fitted Pirelli Phantoms to the new Thruxtons.

I replaced the Michelin Pilot tires on my Ducati with Phantoms at the first tire replacement. The Pirellis never had the "planted", stable feeling of the Michelins. At first it was disquieting, but I just learned to lived with it. The Michelins also inspired more confidence when riding in the rain. FWIW.
 

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Discussion Starter · #12 ·
Thanks for the advice @tsmgguy
Maybe it is just kind of a crappy tire. I usually splurge on tires on my other bikes.
 

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I'll chime it too.

Do you perform your own drive chain adjustments?
If so do you actually check the front to rear alignment when complete, or do you rely on the marks on the swing arm?

If your tires are mounted properly, and in good condition with correct pressures, the next thing I would suspect is improper wheel alignment.

A slight misalignment will not be perceptible until you are at highway speeds. Then it can produce a frontend oscillation or a feeling of vagueness in the directional control.
 

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I'll chime it too.

Do you perform your own drive chain adjustments?
If so do you actually check the front to rear alignment when complete, or do you rely on the marks on the swing arm?

If your tires are mounted properly, and in good condition with correct pressures, the next thing I would suspect is improper wheel alignment.

A slight misalignment will not be perceptible until you are at highway speeds. Then it can produce a frontend oscillation or a feeling of vagueness in the directional control.
I check the chain tightness and alignment using those notches. what is a better way?
 

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A tight string stretched straight from the shoulders of the rear tire past the front tire. the distance to the shoulder of the front tire both behind the front axle and in front of the front axle should be the same on both sides of the bike. That insures that both of the wheels are in exactly the same track. If the axle adjustment is just slightly off it can result in a considerable misalignment at the front end.

You won't notice at 30mph around town, but at highway or race speeds it will noticeably effect stability.

It's an easy procedure to do. The bike has to be upright on the center stand, or pit stand, or have a buddy sit on it and keep it vertical. I have two 5lb dumbbell weights that I use with a vertical pin in each that the string is attached to. You pull the string tight by positioning the weights, then sight along the string from back to front. Then check the distance from the string to the shoulder of the front tire. Repeat the procedure for the other side of the wheels. the distances should be the same or the wheels are not in proper alignment.

The only downside to the procedure is that you have to get facedown on the shop floor to sight along the string and get it lined up properly. Once you're familiar with the process it goes fast.

There are more sophisticated ways of checking alignment. I believe there is a company that sells a contraption made of aluminum channels with screw adjusters and gauges that you roll the bike over and measure the clearances. Great solution for racers, but I like to keep it simple.
 

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Dang man, that's a disappointing feeling to have on a brand new bike. Mine is an R but close enough for horseshoes I suppose to make a comparison. In contrast I can't remember a bike ever feeling quite so planted right off of the showroom floor. Iv'e only tickled the ton for a second or two as I am still breaking it in so mainly keeping it in the twisties but even at highway + speeds it felt pretty stable.

I would definitely look in to wheel alignment, pressures, and also check the steering nut for and looseness. I have found that chain adjustment is mostly felt at lower speed and more so with speed changes up or down.

Also I really like the Pirelli's that the R came with. So if all else fails maybe swap over to them?
 

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I check the chain tightness and alignment using those notches. what is a better way?
The alignment marks are certainly the easiest way, if they're correctly placed. I check them once using the string method above when purchasing a new bike. If they're spot on, then there's no need to use any other method in the future.
 

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This is really stretching but check your motor mounts. This was a known frequent problem on certain models of Kawasakis where the lower rear motor mount bolt broke in tension. The broken bolt remained in place so it wasn't obvious, and the symptoms were exactly as you described.
 

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When I rode my new ST the 70 miles home from the dealer through the hills and curves the handling felt a little strange only in the corners. Got home and checked the bike. Found chain alignment was off a half an alignment mark on one side and the tires were 3 or 4 pounds low on air. I fixed these, now it is more stable and solid in the corners. So much for the dealers uncrate setup check list.
 

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Discussion Starter · #20 ·
Well, got home from vacation.
Checked the tire pressure, both sitting right at 36 psi. So that is okay.
Checked chain alignment and that looked good.
Was going to bring it to my buddy's house because he has a stand to check bearings any anything else, but figured I am going in Saturday and I will let them deal with it.
- Maybe I need to stiffen up the suspension? Maybe it feels soft because it is on the stock setting, I'll have them click it up a notch or two.

Along with the stalling issue. I know others have had issues stalling from idle or the bike dying on downshift. Each has happened to me once and it is a little unnerving. Sounds like a throttle body adjustment and ECU re-adaptation flash should do the trick.
 
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