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Riding a 2009 R1200gs
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If you read all the 12 pages of the AdvRider thread, some managed to get new tanks from BMW. Another one found a very nice way to hide the gap.
 

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Discussion Starter #23
Mine is way out of warranty. I read to about page 7 and then stopped. I will go back and take a read.
 

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Every Ducati owner went through this years ago when ethanol caused their fuel tanks to swell so much the bodywork wouldn't fit and/or the switch gear would hit the tank at full lock. Even went as far as a Class Action Lawsuit in the US against Ducati. Didn't help much. Ducati just settled by extending the warranty on the bikes affected by a couple of years...and would offer to replace the fuel tanks with ones made from the exact same material!
 

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or maybe the piece from the factory just doesn't fit as well as it should. I thought I read in the past that there was a recall for that issue? I know there was something about it and it was BMW's issue, not ethanol. FYI, my 2016 does it too. the sure is ride more worry less.
 

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Discussion Starter #26
As long as the tank is safe I really don’t care. If it is safe and they made a piece slightly bigger to cover the gap....done! I looked my tank over closely and it just did not look to have enough wrong with it to cause the gap. The gaps there and honestly it bugs me to look at it so I have to ignore it because I am not paying 1000 bucks for a plastic gas tank to fix the issue. It is what it is. Its time to ride.
 

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Riding a 2009 R1200gs
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I must admit that I was very skeptical of the ethanol causing swelling, after all, ethanol is shipped in HDPE (High Density Poly Ethylene) containers. It is reported (but I did not check) that the GS tanks are made from HDPE.

I asked an engineer friend (specialised in epoxy resins, not thermoplastics). He pointed me to the following document COMPATIBILITY STUDY FOR PLASTIC, ELASTOMERIC, AND METALLIC FUELING INFRASTRUCTURE MATERIALS EXPOSED TO AGGRESSIVE FORMULATIONS OF ETHANOL-BLENDED GASOLINE

It's a very technical reading, in short, it demonstrate (and measures) that ethanol-laced gasoline really cause swelling of HDPE.
 

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Discussion Starter #28
In your read of the tech data, does it indicate whether it will cause a complete failure or is swelling the biggest issue with HDPE plastic? Is this question more of a who knows than a firm yes or no?
 

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Riding a 2009 R1200gs
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If I understand correctly (plastics are not my area of expertise) some swelling will happen, failure will not.
 

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Yes, that's correct. The ethanol causes some swelling and distortion in many plastic, but it's relatively mild in HDPE. (Just enough to dislodge a tight-fitting plastic panel on a certain motorcycle!) Ducati tried to use PA6 Nylon for their tanks a few years ago. They liked it because it was: cheap, took paint very nicely (HDPE can't be painted, hence the plastic covers) and could be molded into complex shapes. Unfortunately for Ducati owners, PA6 nylon reacts much worse to Ethanol fuels and will swell enough to cause fuel pumps to leak and tank removal for servicing becomes nearly impossible. So they switched to HDPE on many of their models, just like BMW. And they still get some swelling complaints, too. The only real fix is for the manufacture to leave space under the tank covers to allow for a small amount of expansion. Too bad BMW can't figure that out.
 

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Discussion Starter #32
Yes, that's correct. The ethanol causes some swelling and distortion in many plastic, but it's relatively mild in HDPE. (Just enough to dislodge a tight-fitting plastic panel on a certain motorcycle!) Ducati tried to use PA6 Nylon for their tanks a few years ago. They liked it because it was: cheap, took paint very nicely (HDPE can't be painted, hence the plastic covers) and could be molded into complex shapes. Unfortunately for Ducati owners, PA6 nylon reacts much worse to Ethanol fuels and will swell enough to cause fuel pumps to leak and tank removal for servicing becomes nearly impossible. So they switched to HDPE on many of their models, just like BMW. And they still get some swelling complaints, too. The only real fix is for the manufacture to leave space under the tank covers to allow for a small amount of expansion. Too bad BMW can't figure that out.
Well said!
 

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The first steps are positioning the left and right covers.

Then install the centre cover.
I'm also an owner of a 2014 GS, I have been bugged by the same gap issue for a few years now. I've been able to let it go, and just enjoy the ride. Question, where can I get a workshop manual that has those instructions?
 

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Discussion Starter #34
I'm also an owner of a 2014 GS, I have been bugged by the same gap issue for a few years now. I've been able to let it go, and just enjoy the ride. Question, where can I get a workshop manual that has those instructions?
I would like that manual as well.
 

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Riding a 2009 R1200gs
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BMW name their manuals RSD (Repair and Service Data) you can get them from the dealer $$$ or google around, the older ones (not including 1250) lurks on the Internet.
 

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... just to tick off the following box...
... there is an indented channel running all the way up on the right side of the tank just inside of were the edge of the center cover covers... if you have any wires running from under your seat to the front of the bike in the channel, just make sure the wire(s) didn't shift outside of the channel anywhere along the length of it. If so... just align it back in and tape it in the channel where it seems to escape. This is one possibility of why your cover may not be seating.
 

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Discussion Starter #37
That is a very good point. In my case I am all clear regarding the wires. I think this must be the swollen gas tank issue.
 

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Don’t forget that BMW is a European manufacturer and here in Europe the maximal percentage of added ethanol to unleaded fuel is 10 %.
Hence, to my knowledge the issue of swollen tanks doesn’t arise here and is apparently no cause for much concern to BMW.
Moreover , since in most European countries we still have the choice of filling up with more expensive, ethanol free (or max. 5% ethanol ) fuel, I always opt for this variety for my motorbikes and BMW car.
 

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To the OP...yeah it bugged me, too, at first on my '15 GS LC. When I went to change the air filter and put things back together, no matter WHAT I did, I couldn't make that gap go away. Didn't want to get heavy-handed and break a tab or two, so thought I'd just have to put up with it. But, being slightly anal like I am, it bugged me enough to seek a solution.

So, I went here... McMaster-Carr. Got about 10' of part #9141K168 adhesive-backed weather seal. It's something like .125" H x .125" W; $2.38/ft. so not quite 24 bucks for the roll. It comes in black or gray.

As you you can see by the attached photos, a fairly decent fix to the problem!

Cheers,

M'cai
Bend, Oregon USA

ScreenHunter 382.png 20200626_160238.jpg
 

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