Air filter and mpg?

[Ebet]

Hi, folks:

My 2006 R1200RT is about two months old now. When I first got it, it was getting around 41-42 mpg, bu now the fuel efficiency has dropped to 39 mpg or so. I am wondering if this is because the bike had an unusual experience a few weeks ago. The bike (and I) were in a video that required it to be carried up and down two flights of stairs in a warehouse. It took nine guys and a rope, and at some points the bike was in almost a vertical position with the front end pointed at the ceiling. On the way back down the stairs it was pointed front-end-down. They never leaned it too far over horizontally, just vertically. I wonder if this positioning would have caused any nasty fluids to get into the air filter, thereby worsening the fuel effiiency, like what can happens when you drop your bike? Does anyone know? I have no plans to torture my bike like that again but I wonder if I should take it in to the mechanic early or just wait the month or so before it's due for its 6K service.

Thanks and happy Halloween!

[RiverRat280]

oil could've made it way into the airbox but don't think it would affect your mpg that much. Don't know about the RT but my GS has a small plug in the bottom of the airbox to drain any oil out of it. More likely culprit is driving style, maybe rode a bit harder or more stop and go? I wouldn't worry too much about it, make sure your oil level is ok and check the box to make shure it doesn't have allot of oil in it.

[meisco]

I have noticed the last few years a marked decrease in fuel economy during the Fall season. During the Spring and Summer, the mileage kicks back up. At first I thought it was the bike out of tune. After a tune-up, it still averaged as much as 10% less MPG. My commute is pretty darn monotonous, so I can't attribute it to a heavy throttle. In colder weather, the tire pressure tends to be decreased, so I thought it might be that. I pumped up the pressure with no luck. I make sure to fill it up to the same level each refueling. I've switched octane with no change. Air filter. Gas filter. None of these changes had a positive affect in the MPG.

Do the gas stations in LA reformulate in the winter?
Does outside air temperature affect MPG?
What other factors am I missing?

For reference, I average 47-48mpg in the spring/summer (43-44 mpg when not commuting) and 43-45mpg in the fall/winter.

Pete

[nrpetersen]

The air density varies inversely with absolute temperature. The air density at say 90 deg F is 10 % less than at 40 deg F. The result is proportionately greater aerodynamic drag at lower temps.

There are also greater losses in engine and driveline warmup needs at lower temps.

[breyfogle]

....The bike (and I) were in a video that required it to be carried up and down two flights of stairs in a warehouse. It took nine guys and a rope....

LA *really* isn't like any place else !!

[Ebet]

Thanks for the replies!

[meisco]

nrpeterson . . . thanks for the info on air density. This makes sense now. I once did a 200mile+ slab across one of the deserts in the middle of summer (it had to be 115F+) and had some of the best mpgs ever for my bike. It didn't make sense at the time because I thought I was pushing the bike hard and I would have figured it to have very low gas mileage. I attributed it to inaccurate gas delivery at the service station when I finally filled it up.

Pete