12GS Unstable in high speed

[Peak Rider]

Relax

I experienced this effect when I was still using the stock windscreen. Above 70 mph there is much more wind force, aka buffeting, hitting your shoulders. If you are riding with arms and handlebar grip not completely relaxed the buffeting feeds directly into the steering and can exhibit exactly the effect as described by both Milano 33 and John 1215. Try going for a 70+ mph ride with elbows down and relaxed and only a very light grip on the bars. Given the seasonal temperature and road conditions we do tend to ride a bit more tense this time of year.

 

[Pukmeister]

Tight steering head bearings will give you the symptoms you describe.

 

[SPAINSKYWALKER]

Milano33,

I've just bought a new 2008 1200 GS and I know exactly what you are referring to as I get the same feeling. I put it down to my being a well built person and I have been told to increase gradually the rear shock pre-load testing it each time as this will eventually cure the problem.

john1215

Hi,

i agree with this possibility; in In most cases the people forget that many of these problems come from the back part of the motorcycle; (see it first), But also it is possible that you have problems on the brake discs (doubled, for overheating or for fault of manufacture), and then they produce the effect on that you comment.

But also it is possible that you have problems on the brake discs (doubled, for overheating or for fault of manufacture), and then there takes place(is produced) the effect on that you comment. Good luck

V`ss from Spain

Pd. When you find the problem, please tell it.

 

[Gabby]

Tourance exp by any chance

Mine went off at around 2k and was horrendous on the road tanks slappers etc

That can't be the Tourances can it?

I use them and take them right down to 1mm back and front.

Never had a problem.

 

[birdseye]

if it started at 16000km without you having changed something, then I suggest that its a problem of wear on some part of the bike. looseness of some sort which is varying the alignment of the bike whilst on the road. but the problem is finding something like that.

if you have a garage to put the bike in and a pal to help you, then I suggest you systematically work your way from the back of the bike to the front looking at the basics like wheel bearings, play in the bevel box, wheel run out, then suspension mountings and particularly the subframes and their mountings etc. What you are looking for is something that should be tight and was when the bike was new but is no longer.

if its not something obvious you have as good a chance of finding it as the dealer. he cannot afford to spend hour after hour looking for a problem he might not find.

 

[Slowdown]

Like others have said - it's going to be the suspension. Are you sure it's set up properly? Similarly, set the tyre pressures to the tyre manucacturers recommendations, not the one's in the handbook. I find BMW's way too soft.

Mine weaves at >80 if there's not enough preload on the rear, no matter what the loading is.

 

[Milano33]

Hi, many thanks for all your responses, sorry I didnt reply earlier.

Ad: Adjusting the screen:
I have played with the screen position the first 1000miles after I bought the bike, finding the "right" for me and have not changed it since then. So I don't think this is an issue.
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While you are at the front of the bike just check the Torx pinch bolts that hold the fork legs into the bottom yoke - these seem to have a habit of loosening off (its unlikely to be this but elimination is the name of the game)

This has been checked by BMW dealer when replacing the front suspension and the forks oil.
* * *

...as you have spoke wheels, it worth checking the "run out" on them - should be within 3 mm I think - just stick the bike on its centre stand and rotate them for a quick visual...
Good luck

Done that personally and also this was the first thing the dealer looked at. They are within limit. Checked also the balance of the wheels.
* * *

Check the bolts of the bridge holding the forks right above the front fender. If you say the hadlebars at standstill feel soft that might be it...

Will do, whenever I got my bike back, it is stuck with the dealer over last almost 2 monts..
* * *

I've just bought a new 2008 1200 GS and I know exactly what you are referring to as I get the same feeling. I put it down to my being a well built person and I have been told to gradually increase the rear shock pre-load testing it each time as this will eventually cure the problem.
john1215

I agree the "well build" riders may cause a bit different bike behavior, but my bike was perfect the first 16,000km and I did not put on any weight since I bought the bike... And still, Im only 100kg - the bike is not made of wax, is it?
* * *

Tight steering head bearings will give you the symptoms you describe.

This is my estimate too, however the dealer said it was OK...
* * *

... In most cases the people forget that many of these problems come from the back part of the motorcycle; (see it first)

I did and the dealer did; all is tight, in line, no problem...
* * *

... When you find the problem, please tell it.

I certainly will!
* * *

if it started at 16000km without you having changed something, then I suggest that its a problem of wear on some part of the bike. looseness of some sort which is varying the alignment of the bike whilst on the road. but the problem is finding something like that.

Absolutely agree!!
* * *

...I suggest you systematically work your way from the back of the bike to the front looking at the basics like wheel bearings, play in the bevel box, wheel run out, then suspension mountings and particularly the subframes and their mountings etc. What you are looking for is something that should be tight and was when the bike was new but is no longer...

I would love to, but as I said, the bike has been with the dealer(s) for almost 2 months still discovering...
* * *

Assuming it is not something simple (tyres, suspension...etc) I am mainly worried about some cracking in frame and similar...

 

[Pukmeister]

Highly unlikely to be frame cracking/change in frame geometry. Much more likely to be caused by suspension wear.

The standard 1200 rear shock is softly sprung and with limited damping as standard. With age/wear its performance deteriorates rapidly until it has an effect on handling. I am almost 100KG myself and my GS was transformed once I fitted replacement shocks (Wilbers units) based upon my weight and riding style (fast road)with luggage and pillion. Prior to fitting them, the original rear shock was literally shocking (no pun intended) on anything but the firmest setting.

I strongly suspect your rear suspension is not working at its best anymore.

I would say your bike would benefit greatly from replacement shock absorbers. I'd recommend top quality aftermarket items from Ohlins/Wilbers/Technoflex.

 

[Edventure]

same issue

I had the same issue with my GSA, weaving at high speed and generally feeling unstable. I tried changing tyre pressures etc but to no avail. Until........I fitted a set of Wilbers. Bike now steady as a rock regardless of load or speed. Best investment made along with HID's!