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Old 05-15-2013, 05:27 PM   #16
nwpa
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Originally Posted by '05Train View Post
Something's not right. I can ride hands-off at triple-digit speeds and the bike's rock-solid.
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Old 05-15-2013, 05:35 PM   #17
bemiiten
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BMW quit balancing the rear wheel from the factory a ways back. Did they quit doing the front too? New bike owners should return to the dealer and ask the wheel/s be balanced.
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Old 05-15-2013, 05:58 PM   #18
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wobble or vibration?

Your first post said wobble, which I would lump in the < 10 hz range, i.e. tank slap or something like that. If that's the case (like the steering shakes when a semi passes), its inherent in the bike geometry and will always be there. You can minimize it with different tires (knobbies make it worse) or add a steering damper.

Later on you stated that the frequency was 500 hz range, which I would describe as a vibration . This is inherent in the framework and structure of the bike. They all do that . This is where you can try to attenuate the resonance by checking TB sync, adding vibration absorbers to the handlebars, etc. If you are thinking 500 hz, I would start with the sync. According to the REPROM for 2010 GSs, the spec for sync from BMW is friggin huge, and is definitely noticeable from a vibration standpoint. Also, the engine itself smoothes out quite a bit after about 10k miles.
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Old 05-15-2013, 06:23 PM   #19
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Quote:
Originally Posted by justinallen03 View Post
Your first post said wobble, which I would lump in the < 10 hz range, i.e. tank slap or something like that. If that's the case (like the steering shakes when a semi passes), its inherent in the bike geometry and will always be there. You can minimize it with different tires (knobbies make it worse) or add a steering damper.

Later on you stated that the frequency was 500 hz range, which I would describe as a vibration . This is inherent in the framework and structure of the bike. They all do that . This is where you can try to attenuate the resonance by checking TB sync, adding vibration absorbers to the handlebars, etc. If you are thinking 500 hz, I would start with the sync. According to the REPROM for 2010 GSs, the spec for sync from BMW is friggin huge, and is definitely noticeable from a vibration standpoint. Also, the engine itself smoothes out quite a bit after about 10k miles.
I was told by dealer there is no TB sync on the Waterboxer and the service sheets don't mention a TB sync.
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Old 05-15-2013, 08:53 PM   #20
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Originally Posted by hammick View Post
I was told by dealer there is no TB sync on the Waterboxer and the service sheets don't mention a TB sync.
Fly by wire. No cables to adjust for an off idle adjustment. Hasn't been an idle adjustment since the hexheads came out. If the balance is terrible you have an air leak or the valves are way out of whack on one side. Possible other causes, of course.
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Old 05-15-2013, 09:45 PM   #21
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Im trying to find the kevin cameron column on occilations. I paraphrase, but apparently surface imperfections cause deflections of the tire/suspension system with diminishing (its not space so equal opposition is limited) opposite reactions. Trouble is the road is continuously imperfect so almost all bikes when rolling on public non laboratory surfaces will occilate to some degree. Keith Code discusses this too
I roll mine with the cruise control on and take both hands off the bar for what seems like forever. My bike has small movements of the bars that have no effect on tracking in a straight line.
ymmv
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Old 05-15-2013, 09:48 PM   #22
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Quote:
Originally Posted by '05Train View Post
Something's not right. I can ride hands-off at triple-digit speeds and the bike's rock-solid.
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Old 05-15-2013, 10:30 PM   #23
Kaj
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Originally Posted by '05Train View Post
Something's not right. I can ride hands-off at triple-digit speeds and the bike's rock-solid.

I agree. I even have a habit to amuse myself by sitting on the backseat on the highways...other people wondering perhaps if the invisible man is riding the bike.
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Old 05-15-2013, 11:38 PM   #24
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Quote:
Originally Posted by madefrtv View Post
Im trying to find the kevin cameron column on occilations. I paraphrase, but apparently surface imperfections cause deflections of the tire/suspension system with diminishing (its not space so equal opposition is limited) opposite reactions. Trouble is the road is continuously imperfect so almost all bikes when rolling on public non laboratory surfaces will occilate to some degree. Keith Code discusses this too
I roll mine with the cruise control on and take both hands off the bar for what seems like forever. My bike has small movements of the bars that have no effect on tracking in a straight line.
ymmv
This sounds like it. It is a constant oscillation, it doesn't get worse with time or speed. It only occurs at certain speeds at certain roads. Lots of difficult variables, but it has no stability impacts what so ever. It is only noticable (visisble, since I cant't feel it) in the handlebars.
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Old 05-16-2013, 12:38 AM   #25
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Originally Posted by IB1 View Post
This sounds like it. It is a constant oscillation, it doesn't get worse with time or speed. It only occurs at certain speeds at certain roads. Lots of difficult variables, but it has no stability impacts what so ever. It is only noticable (visisble, since I cant't feel it) in the handlebars.
I suspect its endemic to almost all bikes. At least I have had it on every bike i have bothered to notice it on
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Old 05-16-2013, 02:04 AM   #26
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Originally Posted by IB1 View Post
This sounds like it. It is a constant oscillation, it doesn't get worse with time or speed. It only occurs at certain speeds at certain roads. Lots of difficult variables, but it has no stability impacts what so ever. It is only noticable (visisble, since I cant't feel it) in the handlebars.
I think if this whole sad K Ash thing had not happened I would not even being concerned about this.

I will get some highway time this weekend and try to narrow it down a little better.
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Old 05-16-2013, 02:05 AM   #27
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Originally Posted by madefrtv View Post
I suspect its endemic to almost all bikes. At least I have had it on every bike i have bothered to notice it on
My previous bike didn't have cruise control, so I didn't ride handsfree. But it had lots more vibrations coming through the handle bars. Now that I come to think of it: On the old bike I often took my left hand of the handle bars and then the clutch lever vibrated, this didn't happen with my hand there.
It probably has got something to do with the resonance freq of the handlebars.
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Old 05-16-2013, 02:07 AM   #28
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I think if this whole sad K Ash thing had not happened I would not even being concerned about this.

I will get some highway time this weekend and try to narrow it down a little better.
I never noticed this at the highway. The speedrange this happens on mine is a little below highwayspeed.
And in my region it is way to windy lately to try and find out.
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Old 05-16-2013, 05:50 AM   #29
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I never noticed this at the highway. The speedrange this happens on mine is a little below highwayspeed.
And in my region it is way to windy lately to try and find out.
I just came back from a 100 Klm run with the local sports bike club, lots of twisties and suburban main roads and about 5 Kim of freeway.

I could not get the bike to exhibit any wobble in the bars tonite.

I note that my front tyre was showing 2.1 bar and rear at 2.5 bar. Last nite the front was at 2.2 bar, can't imagine that is significant just thought I'd mention it.
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Old 05-18-2013, 03:53 AM   #30
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I just came back from a 100 Klm run with the local sports bike club, lots of twisties and suburban main roads and about 5 Kim of freeway.

I could not get the bike to exhibit any wobble in the bars tonite.

I note that my front tyre was showing 2.1 bar and rear at 2.5 bar. Last nite the front was at 2.2 bar, can't imagine that is significant just thought I'd mention it.
I also came back from a 300km ride, all types of roads twisties , Hwy and back roads and speeds up to 180kph (on a private road of corse ) no wobble for me
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