'Must do' fuel tank mod

Tim Cullis · Dec 5, 2004

I've stuck this up as a separate thread as the original is not obviously titled.

My fuel range has typically been 160-170 miles before the reserve light comes on.

Yesterday I did the fuel tank mod as described by Dutchman and was for the first time able to completely fill the tank. On today's ride out I did 199.5 miles before the reserve light came on, indicating an overall range of 245 miles.

Well worth doing.

Another thread on fuel tank range: http://www.ukgser.com/forums/showthread.php?s=&threadid=32575

Tim

GSmonkey · Dec 5, 2004

Sounds like a good mod.

Haven't ventured into taking any of the panels off yet (still to get instruction manual from BMW to show me where fasteners are I hope) so won't be doing the mod yet.

Am I right in thinking that you can pull the filler neck out far enough to see both sides and hence drill through without getting any swarf in the tank??

Tim Cullis · Dec 5, 2004

It takes only 5 minutes to get the tank bits off, follow instructions in Dutchman's thread.

I also removed the rubber insert at the bottom of the filler neck (stick your finger in and pull upwards) which must have created a few more centilitres of fuel space.

Tim

GSmonkey · Dec 5, 2004

I shall give it a go when I have a free weekend. Sounds like a good mod............I hate filling up. Just got rid of a CBR6 which required filling every 110miles

Tim Cullis · Dec 7, 2004

Following the first post in this thread, I thought I would see just how far the 12GS would go after the tank mod.

I was nearing 0 miles to go on the reserve warning, so I went out today with a litre of petrol in the back to see how accurate the reserve calculation is. I had panniers and top box on, all in the 'parachute brake' extended position, and used Pevensey bypass so I wouldn't be endangered when the fuel finally ran out. Speeds varied from 50-60 to above 80.

'0' miles to go came up at 243 miles. When the fuel finally ran out the engine completely died--no spluttering warning. I was doing over 80 at the time so was able to coast some way, and came to a halt having covered 257 miles. So on my bike there's 14 miles left once the range hits 0 (your experience may differ

) .

I chucked in the litre of petrol, waited a few seconds, and the engine started without any problems. The nearest garage was less than a mile away. I refilled the litre container, then filled the tank. Altogether I put in 23.1 litres. Wow.

Tim

Mouse · Dec 7, 2004

GSmonkey said:
Sounds like a good mod.

Haven't ventured into taking any of the panels off yet (still to get instruction manual from BMW to show me where fasteners are I hope) so won't be doing the mod yet.

The black plastic side panels have 4 fasteners - the two "quick release" type that are visible at the rear, a push type at the front top, and a twist type at the front bottom.

To remove: undo the two rear quick release fasteners by turning anticlockwise. Undo the front lower one by reaching underneath the panel at the bottom front corner, and turning the knob through 90 degrees (either direction). Finally pull the top front corner of the panel firmly away from the bike.

The rest of the panels over the tank are held on with torx head screws, there should be a tool in the toolkit to remove these, unless you have the new cheapo version of the toolkit!

When reassabling the plastic side panels, engage the fasteners in reverse order. Also note that there are two clips along the top edge that mate with the side edge of the beak. It's a knack to get these back on properly.

GSmonkey · Dec 12, 2004

Mouse said:
The black plastic side panels have 4 fasteners - the two "quick release" type that are visible at the rear, a push type at the front top, and a twist type at the front bottom.

To remove: undo the two rear quick release fasteners by turning anticlockwise. Undo the front lower one by reaching underneath the panel at the bottom front corner, and turning the knob through 90 degrees (either direction). Finally pull the top front corner of the panel firmly away from the bike.

The rest of the panels over the tank are held on with torx head screws, there should be a tool in the toolkit to remove these, unless you have the new cheapo version of the toolkit!

When reassabling the plastic side panels, engage the fasteners in reverse order. Also note that there are two clips along the top edge that mate with the side edge of the beak. It's a knack to get these back on properly.

Cheers mate.

The mod is done. Only managed to get one hole sorted.....I ended up breaking three bits. Not quite sure whether I should have drilled from the outside of the in, rather than inside out.

Anyway, its now done and I await to see improved tank range. I've just been to fill up and the fuel certainly went in easier. When I'd finished filling the fuel was to the top of the neck!! Still a bit of a pain to get the last bit in though.

Cheers for the encouragement anyhow.

Mouse · Dec 12, 2004

I found it much easier to drill from the outside, you can get the bit perpendicular to the surface.

It's certainly made it easier to fill my bike up, and without going mad I'm getting an extra 20 miles o the tank I reckon. Which is good

GSmonkey · Dec 12, 2004

Mouse said:
I found it much easier to drill from the outside, you can get the bit perpendicular to the surface.

Yes - I realise this now, but why I didn't realise it whilst wasting 3 drill bits I don't know. Still go to take the thing to bits again to drill one more hole I think.

Was quite happy about how easy it all came to bits. The panels come off easy, once you know which ones pull of and which ones have fixings. Could probably have it stipped down again in 2 min no problem.

Colin O · Dec 12, 2004

Is there a downside to this? Is there a reason why the tank shouldn't be brimmed right to the top?

Mouse · Dec 12, 2004

Yes - the spare space in the tank is to allow for expansion if the fuel gets hot, and to allow some room for it to slosh around before it goes down the overflow pipe. You might find if you brim your tank and then put the bike on the side stand, fuel will come out of the overflow.

So it's best only to fill it very full if you know you are going to ride a fair distance immediately.

motozen · Dec 14, 2004

Has anyone managed to capture this process in photos, step by step? Maybe a link to someone's website with clear photos? It would surely enlighten those who suffer from a limited (i.e. lack of) imagination! If I understand the procedure correctly the filler neck must be raised from its perch, in order to drill the holes from the outside towards the center where the petrol nozzle is inserted. Is this correct?
Any photos would be greatly appreciated.

GSmonkey · Dec 14, 2004

It really is easy to do. Once you've got the plastics off, the filler neck lifts up and inch so you can work on it.

I might be having anther go (drilling another hole) on Thursday, if so, I'll try to remember to get my camera out.

Dinger · Dec 15, 2004

Zmeagol said:
'0' miles to go came up at 243 miles. When the fuel finally ran out the engine completely died--no spluttering warning. I was doing over 80 at the time so was able to coast some way, and came to a halt having covered 257 miles. So on my bike there's 14 miles left once the range hits 0 (your experience may differ ) .

Running out of fuel smegs up the cat y'know.

GSmonkey · Dec 15, 2004

Dinger said:
Running out of fuel smegs up the cat y'know.

Seems like the best excuse to rip it out and install a Y-Piece

Mouse · Dec 16, 2004

Would you know if the cat was working or not? Bikes aren't emisions tested at MOT time.

Tim Cullis · Dec 16, 2004

Dinger: A small group of us are Morocco-bound next May, so the cat stands a good chance of getting thoroughly abused anyway.

Motozen: I drilled my holes from the inside, for pic see Dutchman's original thread. The only reason that you MUST remove the panels and lift the neck of the tank is to check the location of the overflow pipe so you don't drill into it.

Tim

GSmonkey · Dec 16, 2004

I managed to get through three bits trying to drill from the inside, but managed to get one drilled. I'd recommend drilling inside out, either way you have to take the filler cap off and once that's off the tank cover comes away in one peice.

I must admit, I didn't realise that bikes were exempt from emissions. Why have BMW put the cat on then???

Mouse · Dec 16, 2004

As a sop to their corporate conscience? Catalytic converters are a waste of time, making one causes more pollution that it will prevent during its lifetime.

motozen · Dec 16, 2004

Motozen: I drilled my holes from the inside, for pic see Dutchman's original thread. The only reason that you MUST remove the panels and lift the neck of the tank is to check the location of the overflow pipe so you don't drill into it.

Tim [/B][/QUOTE]

Thanks Tim, I saw the pic posted by Dutchman, but I'm wondering when drilling from the inside, one must only drill the shown holes, or drill on through to the other side? Hence, a step by step pictorial would help those less fortunate! If anyone has managed to document this process or will be performing this mod and would like to take pics and post them, I'm sure others would also like to see that!

'Must do' fuel tank mod

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