Poor Fuel Economy R1150GS

[clivewhilde]

I have searched past threads for the last hour back to 2005 and not really found what I'm looking for so any help would be appreciated.

I have just come back from Spain on my 2002 R1150GS, 2 days there, 11 days with the wife and kids and 2 days back. I'm loaded up with panniers and Givi topbox and the bike has an overdrive 6th. If I hold it on motorways at 5000rpm (110 on the speedo and 100 acc to Satnav) I get 36-38mpg. The best I achieved at 4000rpm being very saintly over the 3000 miles was 43mpg. Even on the twisty stuff and slower roads I couldn't do better than 40mpg or just under.

I probably wouldn't bother any of you except that this is my 2nd GS bought from a reliable one owner at Christmas. My first GS owned from new by me, also a 2002 model (even the same colour so its not that) had the sports 6th gear and returned 47mpg all day. Even when sat at 6000rpm on motorways with luggage etc.

The bike was serviced by BMW in Grimsby before I bought it, all fluids etc and I only put 1500 miles on it. I had noticed poor economy in that time so changed the plugs and the oil and checked the valve clearances (all spot on) before I set off. I have not checked the air filter or fuel filter.

I can't accept that this overdrive bike does worse mpg than my original non overdrive machine, there must be something wrong. The bike feels generally underpowered but I put that down to sports bikes between GSs. Both bikes have standard can and cat, both bikes always ran a top box at all times. My original bike did have the cylinder heads replaced under warranty for premature valve guide wear because I kept complaining about top end noise and to be honest this latest bike is as noisy. Could that be it?

What can I check, I'm loathed to take it to BMW without having a crack at it first. I've seen TB balancing mentioned, could this be it, how is it done? Also would Steptoe's jumper cable make any difference?

Thanks in advance

Clive

 

[ianboydsnr]

is it single or twinspark?

 

[Packer]

On my 03 1150 twin spark with overdrive I reckon to get 250 miles from the standard tank cruising at an indicated 4,000 but without the rear can, just running a stubby pipe and the cat. That is with System panniers and oversized lids but no top box.

Equates to around 47mpg. The absolute maximum I've had from one brimmed tank was 279 miles when it ran dry, 52mpg, but a lot of that was very gentle due to torrential rain.

 

[RickG]

I wouldn't be surprised by low milage at 100mph with full luggage. Anything over 90 knocks it down significantly. I used to get 250 to the tank with a mixture of fast motorway and city traffic so your are being hard done to at the moment.

Balancing the TB's won't make any difference to fuel consumption, neither should worn guides.

You checked the plug colours? Both the same or one darker indicating running rich.


I'm sure Mr Steptoe will be along to put you right but all I can think of is: duff temp sensor, faulty fuel pressure reg' (delivery pressure too high) , badly blocked air filter, or even a weak spark or two,

 

[John Armstrong]

Lambada sensor?

 

[Pekkavee]

First thing to check is syncronization of throttle bodies.
Is the throttle cable all right, the cablecover not lifted above the nipple.

Pekka

 

[Colban]

If it wasn't for the fact that you got better consumption out of your previous GS under similar conditions i would simply say it was down to aerodynamics.Ie,a GS doesn't have any and that's the reason for the fuel use.
Is it single or twin spark?.
Is the TPS set correctly?.
Air cleaner replaced on schedule?.
Are the plgs the correct colour?.
Valve clearances/end float/TB balancing can make a difference to noise levels,smoothness,driveability and economy.Are yours OK?.
Lambda probe in exhaust?.If it isn't sensing the right amount of oxygen in the exhaust,it pumps more fuel in. (I think that's how it works).

 

[clivewhilde]

Thanks to all so far.

Both bikes were single spark, not twin. The bike was dealer serviced before I bought it but I changed the plugs, oil and filter before setting off. Both plugs looked OK, no difference between the two.

If it is the Lambda sensor, how can this be checked?
Is it possible the engine management system has gone in to safe mode at some point and need re-setting?

 

[Steptoe]

I If I hold it on motorways at 5000rpm (110 on the speedo and 100 acc to Satnav) I get 36-38mpg. :

This is pretty good at those kind of revs.

The minute you go above 4K revs you drink the go juice at a very fast rate.

 

[What Speed Limit]

well i have a 2000 import from holland, pushing around the Manx roads i get about 280km per 21ltrs, when giving it large down the concrete slabs of england i get about 300km per 21ltrs, taking it easy about 120kmph i get about 350km per 21ltrs. this seems quite constant, and has been since i have had it (about 5 months)

any help?

 

[611735]

I think mines brill 165 miles till my warning light comes on the Blackbird was any thing from 90 to 140 max b/4 warning light appeared

 

[Philby]

How about coincidence. I've just come back from a two up tour of Germany and the Austrian Alps this last Saturday, just finishing up with 2054 miles over a 10 day period that involved a bit of golf and Alpine walking. Ahh, back to the bike - because like a lot of the guys here I'm verging on OCD I took the mileage each time I topped up the tank.

To avoid inserting a numbing spreadsheet here I can say that the bike went from 38.3 at worst (flat out down the autobahn one up at 115mph - followed by a two up 105mph cruise to Munich the following day) to 55.0 at best bimbling through the Alps not going over 4000rpm.

So if I told you it did 46 to 52 mpg running at an average 85-90 cruise touching 100 every 20 mins or so that should be a normal consumption. When you get past 100 - 105 it really gulps the fuel. And here's my query from 105 to 110/115 takes another handful of throttle and feel like its being dragged through treacle. So much so the additional speed isn't worth it. This all happens fully loaded two up - I'm 6' 3" tall and broad shouldered (can't call it chubby just yet) so the drag must be incredible.

I did all the oil changes, air and oli filter - even valve clearances but it still feels wooly over 5000 rpm. I've sort of given up and learnt to accept it. BUt like Clive I just have a nagging feeling that it was more spritely 20000 miles ago.

Tell me what you think

Philby - 2003 1150 GS twin spark (28000 on the clock)

I've another story about the 605 mile run back from the Sachsenring this July with my sports-bike mates and what that does to a one up GS - but I'll save that for later.

 

[Carl]

I think mines brill 165 miles till my warning light comes on the Blackbird was any thing from 90 to 140 max b/4 warning light appeared

You want an Adventure tank. 290 until the light comes on

I
I have just come back from Spain on my 2002 R1150GS... If I hold it on motorways at 5000rpm (110 on the speedo and 100 acc to Satnav) I get 36-38mpg.:

I've seen close to 58 mpg while bimbling around Scotland fully loaded with me (16 stone) and a weeks worth of camping gear, food, beer etc. 51 - 53 mpg is normal for mine, although I rarely go above 90, anything more is just hard work on these bikes and as others have already said they really drink the juice when 'making progress'.

Something like an FJR would be a much better for continental blasts at ton-up speeds.

 

[GhostCav]

You want an Adventure tank. 290 until the light comes on

I get at best 250 with my GSA, I think this is probably still due to getting used to the bike after Fireblade's before. I just cant quite get the knack of accelerating smoothly yet & tend to yank it open a fair bit.

Mind you it could probably do with a tune up & replacing the left hand dented in exhaust downpipe.

 

[Rugged Path]

I don't have a problem with fuel costs because we make's it.

GSA's are more sexier in black though.

 

[clivewhilde]

Cheers Philby, I'm 6'7 and 17 and a bit stone. The thing is why does the new bike with overdrive perfrom so much more badly than the old bike without? There must be something wrong and so far I haven't received any suggestions of what to look for or how to tackle it.
Cheers
Clive

 

[Steptoe]

Cheers Philby, I'm 6'7 and 17 and a bit stone. The thing is why does the new bike with overdrive perfrom so much more badly than the old bike without? There must be something wrong and so far I haven't received any suggestions of what to look for or how to tackle it.
Cheers
Clive

Could've been something wrong with your 1st GS