BMW R1200RT/R1250RT Forum

Hi all!  I'm a year-round (until it snows) kind of rider in Canada, and am wondering if any of you have observed something similar to me.  I have a 2010 R1200RT camhead, and in the last few weeks, I've noticed a variance in mileage that I get, depending heavily on the ambient temperature.  It seems I get much better mileage - close to 500km per tank - when the weather is warm - 20 degrees Celsius or warmer.  The warmer it gets, the better my mileage gets.  When it gets cooler - below 10 celsius - I find the mileage suffers quite a bit.  I might get 400km per tank if I am easy on it.  I wonder if this is the fuel injection adding more fuel to keep the engine at proper operating temperature.  I'm not complaining, because no matter what the temperature is, hit the starter, and it never fails to go, and performance seems to be linear no matter the temperature.  Cooler weather seems to provide a bit of a torque bump, as I would expect it should with more dense air. 


What have your observations been?  Mine are not scientific, by any means, just rough approximations.


Just curious.


Marlen (from Canada).

Marien,  What part of Canada?  My Sis, and once my Mom, live(d) in Vancouver, B.C.  Second home to me; took a ride on the bike up there each summer since forever.  I call myself and my ilk Canuckleheads, Canadaphiles, etc.  Great country, even greater music.


I'm in Northern California, so am a legit 365, rain or shine rider (not to rub it in).  Haven't registered my car in nine years now;  too frustrating driving a car when you can legally split lanes, avoiding the terrible California drivers) and park anywhere on a bike.  I've only recently purchased my R1200RT, but previously  I've done a LOT of riding in really hot weather (43 degrees Celsius and up) and have also noticed the same phenomenon:  significant increase in mpg.  I found it quite counterintuitive;  I thought it would have decreased efficiency.  I would be curious to hear the science of it.  Like you, all my evidence is anecdotal.  I should add that all my touring was on naturally-aspirated bikes (your fuel-injector theory is interesting, though), with the last 17 yrs. on an 1100cc Honda Magna (liquid-cooled).


I'll be interested to see if someone chimes in with a technical explanation.  Ciao.

This article could provide some answers:- https://www.scientificamerican.com/arti ... economy-o/


Not all relevant to bikes but tyres, lubricant viscosity and even drag will be.

Cooler air, being denser, will increase engine efficiency but the cooler denser air will create more drag thereby cancelling out the thermal efficiency increase. Once a water cooled engine reaches operating temperature the water is much slower than air to lose energy (heat). I think the air cooled engine is being enriched a bit in air that is super cooled (remember chill factor). And a water cooled motor will close off the radiator allowing the water to absorb and retain heat. But we should not see the same effect on a carb fueled motor. Not monitored and micro-adjusted. At your next rally look at the exhausts. Especially the earlier boxer injected and compare to the same year carb bike of any brand.

Just thought I would add my observations, 2010 air-cooled. Ride it throughout the year and pretty well the same journey in similar traffic conditions. The air temperature range has been during the commutes, 34c to -10c, hottest was a run down to Lucca in Italy when it hit 38c. I used to watch the fuel consumption diligently and then gave up as it was consistently between 52 - 56mpg over the first 18 months, this was using my spreadsheet and not the display. The speeds were stationary to the "legal speed limits".The engine temp once warmed stayed on 2 bars and only hit 4 when I was getting up to the entrance to the Mont Blanc tunnel in heavy traffic in 34c. The run to Lucca and back didn't change the fuel consumption, 80-85mph on French motorways. I suppose theories could go from fuel types being changed for seasons, air density, oil viscosities, tyre pressures, winter tyres etc...

I'm in Edmonton, Alberta.  Northern climate - there's snow in our impending future, for sure, just not sure how long until it lands.  Sometimes I get to ride into November, and start again regularly riding to work in March or so.  "Winter IS coming"... 
:eek:

jackronner wrote: Marien,  What part of Canada?  My Sis, and once my Mom, live(d) in Vancouver, B.C.  Second home to me; took a ride on the bike up there each summer since forever.  I call myself and my ilk Canuckleheads, Canadaphiles, etc.  Great country, even greater music.


I'm in Northern California, so am a legit 365, rain or shine rider (not to rub it in).  Haven't registered my car in nine years now;  too frustrating driving a car when you can legally split lanes, avoiding the terrible California drivers) and park anywhere on a bike.  I've only recently purchased my R1200RT, but previously  I've done a LOT of riding in really hot weather (43 degrees Celsius and up) and have also noticed the same phenomenon:  significant increase in mpg.  I found it quite counterintuitive;  I thought it would have decreased efficiency.  I would be curious to hear the science of it.  Like you, all my evidence is anecdotal.  I should add that all my touring was on naturally-aspirated bikes (your fuel-injector theory is interesting, though),with the last 17 yrs. on an 1100cc Honda Magna (liquid-cooled).


I'll be interested to see if someone chimes in with a technical explanation.  Ciao.

Haven't gotten to Edmonton, but Calgary and up to Jasper twice (which I found more impressive than the American Rockies - the color of the rivers and lakes!!!).  First time in Calgary, unbeknownst to me it was the opening of the Stampede, and I rode into town from Glacier and was welcomed by thunderous fireworks!  I thought: much appreciated, but how did you know I was coming?  When I brought my Bonneville back from Europe in October of '71, I never even considered registering/insuring it, knowing full well that (back when winter was what they now call snowpocalypse) there would be ice and snow on the ground for the next 4-5 months.  Strangely, and I think this was the beginning of global warming, it was 70 F in mid January, the parents were away and the bike was calling to me.  A New York cop car pulled up and asked me where my license plate was, to which I responded: "Somewhere on the highway in Belgium".  When he told me to pull over, I just dropped it down a gear and lost him after my second turn.  Only time I ever ditched a cop.  Although, with my Magna's alleged top end of 173 mph, I could have outpaced even the cops' airplanes on I-5!!  But sanity prevailed.  I'll be tracking the temps up there and wondering if you've packed it in for winter (hibernating?).

I've ridden in temperatures from 2C to 40C and never noticed any correlation between ambient temperature and fuel consumption.

On the other hand, travelling on back roads at 40 - 50 mph gives more miles to a gallon or tank than thrashing down an autobahn at 80 - 90 mph.  From 57 / 58 mpg down to something just under 50 mpg