GSA Tank conversion problem

[adamhuntuk]

Hi everyone

I have recently converted my 2009 R1200gs to the adventure tank all seams to be working fine apart from my slow steering 20-30 mph. I get the feeling of a flat front tyre and on roundabouts the bike occasionally dips into the turn quite suddenly making me feel like im about to fall off. I have checked the tyre pressures and they are fine so im wondering if is just the amount of extra fuel thats making it do it. I have tried brimming the tank thinking it could be fuel movement but it has no affect. Im open to suggestions as to what this might be?
FAO I have esa on the bike with hyperpro lowering springs which where recently added before the conversion with no problems afterwards. The bike also has a wunderlich adjustable vario paralever arm which again was fine before the conversion.

Cheers

Adam

 

[Bendy toy]

The extra weight of fuel might make the bike ride lower at the front, which can quicken the steering on a bike with boring tele forks. On a bike with telelevers it might not have so much effect so stiff steering is my best guess. However, 15 litres extra fuel is only about 12Kg and the tank itself isn't hugely heavy so I'd not expect a massive weight imbalance on the bike as a whole.

A bike with stiff steering bearings or something binding will steer in all sorts of strange ways. Having had the tank off etc it might be there is something binding in the steering department.

 

[Pukmeister]

I think the GSA has slightly different steering head geometry, possibly because of the slow steering issue you describe?

 

[adamhuntuk]

The extra weight of fuel might make the bike ride lower at the front, which can quicken the steering on a bike with boring tele forks. On a bike with telelevers it might not have so much effect so stiff steering is my best guess. However, 15 litres extra fuel is only about 12Kg and the tank itself isn't hugely heavy so I'd not expect a massive weight imbalance on the bike as a whole.

A bike with stiff steering bearings or something binding will steer in all sorts of strange ways. Having had the tank off etc it might be there is something binding in the steering department.

Thanks Bendy - Im pretty sure the problem is caused by the conversion as i dont ever remember it snatching before. It was the flat tyre feeling which made me think it was a weight issue. I will have the bike up on the ramp tomorrow and see if i can spot something catching. Would it be worth putting the esa in off road mode to see if the increase in ride height affects the handling?

 

[adamhuntuk]

I think the GSA has slightly different steering head geometry, possibly because of the slow steering issue you describe?

I will have a google and see what i can find out, cheers!

 

[adamhuntuk]

Had the front end up in the air today. Steering is free and smooth. I have checked all bolts are torqued up and also tried adjusting the suspension settings with no luck. Does anyone have any other ideas of things to look at? Cheers.

 

[flatdog]

I know you have checked the tyres, just double check pressure is exactly to manufacturers spec or slightly more.
With the additional weight if it feels like an underinflated tyre then thats what I'd check.

Saying this from experience, with my 1150, went from the std 20 ish l gs tank to a 41 l touratech, and even a coupl of lbs under pressure gave me the same feeling you experience with my tank full.

 

[adamhuntuk]

I know you have checked the tyres, just double check pressure is exactly to manufacturers spec or slightly more.
With the additional weight if it feels like an underinflated tyre then thats what I'd check.

Saying this from experience, with my 1150, went from the std 20 ish l gs tank to a 41 l touratech, and even a coupl of lbs under pressure gave me the same feeling you experience with my tank full.

Hi Flatdog, The front was at 2.5 and is now at 2.7 and still made no difference.

 

[big pete]

On my 1200 adv when i fill up from empty i have to be careful when entering roundabouts or tight bends for the first mile or so, just the weight of a full tank .

 

[Deleted account 190920001]

Run it down or syphon it to a gallon left in the tank. This is lighter than a stock fully fueled GS and if it is still the same it isn't a weight issue. Something else must be causing the problem.

 

[adamhuntuk]

Run it down or syphon it to a gallon left in the tank. This is lighter than a stock fully fueled GS and if it is still the same it isn't a weight issue. Something else must be causing the problem.

Good idea thanks! I need to run it down anyway to let the fuel strip sort its self out so will report back when done! thanks for all the replys so far

 

[Deleted account 190920001]

You haven't just put a new front tyre on at the same time as all the other work? My bike is all over the place for a 100 miles or so with a new front on.

 

[adamhuntuk]

Nope, same front tyre which is not even half worn.

 

[Neil W]

Its not a continental trail attack on the front I had loads of problems with mine after about 800 miles

 

[adamhuntuk]

Its not a continental trail attack on the front I had loads of problems with mine after about 800 miles

Hi Neil, its the standard tourance on both front and rear.

 

[Neil W]

I wonder if it is the combination of the weight of the tank /fuel plus the lowered hyperpro springs screwing up the geometry. On my GSA the full tank makes no difference to handling nor is there a problem when running it on 17" front and rear wheels and road tyres

 

[Bendy toy]

I've just been out on my 2008 GSA on some narrow South Devon lanes. I got above 50mph maybe two or three times in 40 miles. The petrol tank was brimmed before I started out.
Roads were often gravelly down the middle & some potholes but all hard surfaces.
Handling has been superb no dropping into bends and if a wheel slips no drama.
My riding pal on Aprilia Pegaso 650 (arguably much more suited to the roads) was at times struggling to keep up. I wasn't trying hard.
My bike has standard GSA ESA suspension. Rear has 20K miles; front is the original having done 48K with the bike.
The Pegaso has Revs Racing rebuilt front forks and a Wilbers back shock.

Both bikes have the handlebars tipped forwards - moto cross style. Neither of us like the pulled back bars in the crotch feeling many people use on BMWs.


Sent from a widget that can't spell.

 

[Pat J]

Surely the geometry on a standard GSA will be different to a lowered GS as the GSA will ride higher as standard and you'll be putting more weight over the front of your bike with your set up.

 

[Deleted account 190920001]

Surely the geometry on a standard GSA will be different to a lowered GS as the GSA will ride higher as standard and you'll be putting more weight over the front of your bike with your set up.

The whole bike is lifted and not just the back likewise the whole bike is lowered on a lowered bike. That's not to say the geometry isn't different, I don't know, but if it is its not because it is taller.

This isn't the first GS to be converted so I am pretty sure if simply bolting on a GSA Tank caused major handling problems it would be pretty well known.

 

[Hemuli]

I have done similar tank conversion roughly 150000km ago and have not had any problems like you describe.
My bike is 2005 R1200GS. Even with full tank bike is handling nicely (I have Öhlins suspension back and front, so that might make a difference...).