► Fuel efficiency, range and octane questions

[chrisjk]

1000+ miles and averaging 58 mpg mainly on country lanes

 

[Argonaught]

I'm at 700 miles now, showing 52mpg average over that time, & I got 198 miles from the last full tank (which took 16.75 litres yesterday still showing 8 miles left in the tank)

I ride in town 60%, motorway 30% & green lanes 10%...

I'm very happy with that, it was one of my only concerns with the bike, the tank range, but in real world riding getting 200 miles from 16 (+) litres.... that's great.

What a machine!

 

[HR0]

a tardis tank what we all wanted
16 litres on the ouside 16+ on the inside

 

[EmmettC]

I ran out of petrol a few days ago up north, it did 253.5 miles before I stopped a mile from a petrol station. It took almost 17L to fill it.

I have done 3,400 miles now, and it's averaging 61mpg

 

[John Armstrong]

Has anyone checked their MPG while running panniers of any kind?

I've had my mileage drop a fair amount on other bikes after adding bags and am interested in the effect on the 800. The fuel range being reported is right at the edge of what my riding requires, so my luggage choices will be in a large part based on how it affects my range.

Hi

There is the option of bolting two of the Touratech 2 litre cans, and adding 25% to your fuel capacity in one easy / cheap hit

 

[Tim Cullis]

I'm shortly taking delivery of a new F650GS and planning to use it for the HUMM orienteering event in the Pyrenees in July. The other three in our teams are riding 1150GSA, 1200GS and 1200GSA, so it will be interesting to have a real world direct comparison, both cruising at speed, and also bumbling along in the hills.

I understood the 800 performance/economy specifications are based on 95RON fuel, whilst those of the 650 are based on 91 RON. I would have thought that unless the engine and its management system is designed to take advantage of it, there's no advantage. Otherwise surely BMW would do that and publish the better results?

Tim

 

[Ali-bear]

Just thought I should point out that the "octane rating" of fuel is specified differently in different countries.

See: http://en.wikipedia.org/wiki/Octane_rating

 

[Tim Cullis]

... In many parts of Europe, 95 RON is the minimum available standard, with 97/98 being higher specification (being called Super Unleaded)....

... the United States, Canada and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-92 in Europe ...

I can see that RON isn't used as a universal octane measurement, but it is standard across Europe. The problem lies with what people read into the name 'super unleaded' which in the UK normally refers to 97 octane!

BMW states in its specifications
- Super Unleaded (95 RON) for the F800GS and
- Normal Unleaded (91 RON) for the F650GS

The way I read this is that the F650GS will run on US 87-octane fuel (~91 RON in Europe) and if anyone is sticking 97 octane in an F800GS then they're wasting money. But feel free to argue

Tim

 

[Ali-bear]

But feel free to argue

OK then!

The posh unleaded keeps better than the standard stuff, thanks to the latter lacking certain additives. Apparently ordinary unleaded only 'keeps' for 6 weeks or so. This may be a factor in starting a bike after the winter lay-off.

So its not entirely a waste of money

 

[Chris G]

Did a simliar run out test on mine,

222 miles till empty, 3 mile left on the computer when the bike started to splutter, filled up with 17.25 litres from then

 

[Fran1008]

HI!!!

I finally got my bike last Friday evening.

On Saturday I drove 402 km with one deposit, filling 15,2 lts after. It was a route 20% highway at abt 120km/h, 70% secondary roads ranging 3-5.000 rpm and 10% city.

Today (yesterday) I left work at about 19,30 and rode about 175km with about the same % but the computer shows petrol for another 195 km (total 370 km)... I THINK IT IS NOT BAD!!!!

AH, and I LIKE THE BIKE!!!!!!!!!!!!!!!!!!

Regrads

Fran

 

[Tim Cullis]

F650GS - 271 mile range, 17.8 litre tank

I'm having a great time on 'The Hooligan' and tend to be riding in a more spirited fashion than on my 1200GSA. Despite this, fuel consumption on the first tank full averaged 67 mpg for a mix of town/city, country roads and motorways.

For the last 50 miles the fuel computer had been constantly predicting a total range of 265 miles and at said mileage the range went to zero. So I kept going, doing 60 mph against a 20 mph headwind. The fuel finally ran out at 271 miles.

After sticking my emergency litre in the tank (spilled a tiny bit) I rode two miles to the nearest petrol station where I refilled my emergency bottle, then the tank. It took 18.00 litres in total. I have to take into account the two miles I rode (.15 litre?) and the tiny bit I spilt (maybe .05 litre), so the actual fuel tank capacity with the bike on the side stand and getting every last drop into the tank is a massive 17.8 litres.

Tim

PS: the best mileage I recorded touring with luggage on a 1200GS was 284 miles and that was after doing the tank mod to increase the capacity to 23.1 litres. On the 1200GSA I managed a tank capacity of 37.3 litres and did 50+ miles on empty...

Tim

 

[WoodWorks]

Thanks for being the crash test dummy there, Tim. That mileage is great news. The most I ever got on my old R1100GS (before I mounted the Adventure tank) was 235 miles. I got lucky that time, and managed to coast downhill into a gas station after the engine sputtered to a stop.

~270 miles?

David

 

[Fran1008]

Hi,

I did manage 402 kms(abt. 243mls) on 15,5 liters after the first refuellling.

After the second... 375 kms (abt. 230mls)

We will see how about the third

Cheers

Fran

 

[GS800NR9]

I'll have to try running mine dry one day. The 800 and 650 are supposed to have the same tank size but i've never been able to get more than 15 litres in when filling up at about 210 miles.

Maybe the pipework from tank to injectors holds a couple of litres if you run it dry...

The BMW website says 3.8l /100kms @90km/h for the 800 (or 3.7l/100kms for the 650 )which works out at 421km for 16 litres or 263 miles .


BTW , my fuel guage only ever shows a max of 136 miles to empty, never 265. It just sits there on that figure until i've done about 90 miles though then starts counting down. Anyone else have this?

 

[Tim Cullis]

According to the manual "the system cannot tell exactly how much fuel is on board when the tank is completely full. Under these circumstances the display shows a minimum range figure prefixed by a > symbol."

Mine's currently showing >170 miles.

I wonder if someone will come up with a way to squeeze more into the tank of the 650 like the 1200GS' filler neck mod?

The F-GS tank fills to the top a lot more easily than the 12GS, stick the bike on the side stand rather than the centre and go slowly on the final half litre.

Tim

 

[HR0]

hi
does anyone’s bike (F800GS) create a strong vacuum in the tank so that there is a real noticeable suck of air when the tank is opened. to the extent that the tank on the left side "draws in" noticeably under vacuum.

It doesn’t stop the bike from running. I just thought that fuel tanks were happiest at ambient pressure.

I understand from a dealer that there is a vacuum pipe mod to do - but mine is ok ! they’ve looked!

Not really worried just wondering if mines unique

H

 

[Rushy]

Just filled mine up lunchtime today......warning light on for the previous 6 or 7 miles and filled up at bang on the 190mile mark. It took 18.82 litres to fill it. The 190 miles were all very spirited fast twisty B and A road commuting miles during which top gear is almost never used.

190 / 18.82 x 4.55 = 45.9mpg

Oh ...BTW...mine is the heavier 1150 but I just felt like joining in

 

[Tim Cullis]

does anyone’s bike (F800GS) create a strong vacuum in the tank so that there is a real noticeable suck of air when the tank is opened. to the extent that the tank on the left side "draws in" noticeably under vacuum.

I've noticed the sharp intake of air both times I've opened the filler cap. I wasn't aware of the tank drawing in.

Tim

 

[atlatl]

fuel mapping

does anyone have their bike set up for 87 octane fuel? my understanding is fuel economy goes down set up this way, but perhaps if one is using more fuel it would help reduce the chance of unexplained stalls. also is there any harm to being set up to run lower octane fuel but instead running higher octane when available?