Airhead GS - Gas Mileage?

Discussion in 'Airheads' started by summerinmaine, Sep 27, 2004.

  1. summerinmaine

    summerinmaine Hells Atheists MC

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    Wondering what the normal range is for gas mileage on the big airhead. I've searched the archives, but results were inconclusive (too much oilhead data).

    I recently bought a 92 R100GS with a PD tank, and was surprised to see that my range is lower than I expected. I recently ran a test on a one day ride (one up, parabellum screen, 47K miles on motor, 32mm Bings rebuilt less than 4K miles ago, system cases 1/2 full of tools/parts/clothes, mixed freeway and backroad, but virtually no stop and go), and got about 33mpg. I expected closer to 40mpg, but maybe I'm being unrealistic.

    I haven't yet checked the odometer for accuracy, but will start there if I should be seeing better fuel economy. Assuming odo is okay and better mileage should be seen, where should I look next? Check plugs to see if carbies were jetted too rich in rebuild?

    Thanks.
    #1
  2. AnnieGS

    AnnieGS Namasté, bitches!

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    I've got an '87 R80 -- the little blue OM says I should get 48 mpg, but 40 is grounded in reality.
    #2
  3. summerinmaine

    summerinmaine Hells Atheists MC

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    Thanks Annie.
    #3
  4. Jabba

    Jabba "HOLD THE LIGHT!!!"

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    Mine used to get 38 to 42 mpg- depending on flogation level~ shoot a PM to Gringo- he tracks his mileage pretty religiously. '92 PD
    #4
  5. summerinmaine

    summerinmaine Hells Atheists MC

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    Done. Thanks
    #5
  6. dragoon

    dragoon I'm the REAL Dingo Joe

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    '88 GS w/PD tank and 105,000. Got about 36mph fully loaded (the bike was) (I was when we hit camp :freaky ) on my trip to Ouray this summer.
    Carbs were just rebuilt before the trip. Mileage sucked big time before that :nod
    #6
  7. Steverino

    Steverino Arrogant Horse's Ass #1

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    Damn, must have been hell going all that way at 36mph...how long did the trip take? Three weeks?
    #7
  8. dragoon

    dragoon I'm the REAL Dingo Joe

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    You should've seen me when I had that sucker going 48mph :yikes












    jackass :lol3
    #8
  9. Steverino

    Steverino Arrogant Horse's Ass #1

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    That's me......:wave
    #9
  10. Flash

    Flash Sand Boxer

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    36 mph after the carb rebuild?

    78 R100 gets 38-40 mpg. If I get real feather-fisted I can get 43 mpg, but with 6.3 gallons, why bother.
    #10
  11. Eurobiker

    Eurobiker Vintage Cat Herder

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    My 92 GS usually gets 35-36 mpg. Due to the taller gearing, the street bikes do better, IMHO. My 76 R90/6 consistantly would get 41-42 mpg.
    #11
  12. summerinmaine

    summerinmaine Hells Atheists MC

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    I guess that's another data point (or two) that I forgot. I'm usually travelling with the motor in the 5500-6300rpm rev range.

    So far, it sound like I'm in the low end, but not so much so that a fuel leak should be suspected.
    #12
  13. Eurobiker

    Eurobiker Vintage Cat Herder

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    FWIW, at 5K rpm, I'm traveling 77 mph, according to the GPS. No load, other than my arse. :lol3 I don't know if the PD's were geared lower than the stock GS's :dunno
    #13
  14. Jabba

    Jabba "HOLD THE LIGHT!!!"

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    Nope- same gearing.
    #14
  15. Stephen

    Stephen Long timer

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    r75/5: 40 mpg

    77 R100RS: 40 mpg, long-term average. Don't know why I kept so many records on for that bike. On a 5000-mile trip, high was 42 mpg, low was 38 mpg, trip avg 40.000 mpg. Hot, cold, up, down, fast, slow, whatever. Tended to run it at higher rpms.

    88 R100GS: 40 mpg, regardless of how I rode it. Usually lived above 4000 rpm. Most often, well above 4000 rpm. :thumb

    Looks like BMW was designing to a spec, don't it?
    #15
  16. TEXASYETI

    TEXASYETI Call me "thread killer!"

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    91 PD, staying at about 4,000 or 60 mph gets me 42mpg.
    #16
  17. Cpt. Ron

    Cpt. Ron Advrider #128

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    I consistantly get 34mpg while on the highway and twisties. Cruise speed is usually above 5500 rpms. In the dirt and other slow going, it climbs to 40-ish.

    There was some discussion on the airheads mailing list a while back about the fuel economy of the GS's. At least one lister claimed to have a big increase in gas mileage by switching to the 40mm carbs and larger valves (Euro spec) as well as upping the compression ratio (dual plugging too?). Sounded interesting, all BMW parts.....
    #17
  18. clang

    clang Not lost, Exploring!

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    Currently 35-38 mpg on the '92GS with 22k miles - no carb rebuild yet - 33 -35 on the '90PD with 47k and a carb rebuild about 10k ago........

    These are average over all kinds of riding. I track it with every tank of gas on all my vehicles - can be a good early indicator of problems. I think you're in the range. A valve check/adjust and a careful carb sync may bump you up a few MPG...... :dunno
    #18
  19. summerinmaine

    summerinmaine Hells Atheists MC

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    A great resource! Thanks for all the comments. Sounds like my issues are more behavioral than mechanical.
    #19
  20. gaspipe

    gaspipe Wandering Soul Super Moderator

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    My '94 R100GS gets about 36MPG +/- 2MPG depending on how I ride it. It's sorta disappointing, but it's a great ride anyway. I love the bike. It's got that Briggs and Stratton technology thing going on , yet it has nice torque. Maybe it's time to experiment with some Mikunis.

    These bikes sound great with a Supertrapp pipe, if you can find one.

    I find myself riding the F650 Dakar a lot these days since it's getting almost 70MPG.
    #20