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Thread: Speedometer and fuel mpg accuracy

  1. #1

    Speedometer and fuel mpg accuracy

    I bought a 2007 K1200gt this summer and it is my first BMW bike and I am really enjoying it, but I am really disappointed in the speedometer and fuel mpg meter's lack of accuracy. Being German bikes I would have thought that accuracy would be spot on. When I drive 70 MPH my gps on my phone regularly shows me traveling 2 to 3 mph slower. The fuel mpg meter is even worse. The best mpg I have ever seen with this bike is 40 MPG typically 38 or 39 mpg but the mpg meter shows a high of 50 mpg sometimes higher. Is this normal or can these items be adjusted?
    Mike

  2. #2
    Quote Originally Posted by corvair01 View Post
    I bought a 2007 K1200gt this summer and it is my first BMW bike and I am really enjoying it, but I am really disappointed in the speedometer and fuel mpg meter's lack of accuracy. Being German bikes I would have thought that accuracy would be spot on. When I drive 70 MPH my gps on my phone regularly shows me traveling 2 to 3 mph slower. The fuel mpg meter is even worse. The best mpg I have ever seen with this bike is 40 MPG typically 38 or 39 mpg but the mpg meter shows a high of 50 mpg sometimes higher. Is this normal or can these items be adjusted?
    Mike
    The average mpg is certainly off by a lot. But the speedometer sounds pretty typical. Every vehicle I have owned seemed to indicate a few mph higher than actual. I think they do it on purpose to help keep speed in check.

  3. #3
    In the European Union speedometers are allowed to read as much as 10% too fast but 0% too slow. So most BMW speedometers read a few miles an hour too fast to avoid violating the prohibition against reading too slow. In their shoes most people would do exactly what BMW has done.

    As for mpg meters I have never seen one, not in my car, not in my truck, not on my G310gs that is exactly accurate in any short term sense but when I manually compute after a tank of gas they are close enough to tell me whether something is wrong with the way the engine is running.
    Last edited by PGlaves; 09-17-2020 at 02:48 AM.
    Paul Glaves - "Big Bend", Texas U.S.A
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  4. #4
    Fortis Fortuna Adiuvat Omega Man's Avatar
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    Quote Originally Posted by PGlaves View Post
    {snip}...... but when I manually compute after a tank of gas they are close enough to tell me whether something is wrong with the way the engine is running.
    When I mention to people the true way to calculate MPG, Im glad Dumb looks are still free.
    OM
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  5. #5
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    Welcome to the forum from the coast of Kansas. Glad you decided to join us.

    As for your speedo accuracy, as others have said: most, if not all speedometers, are purposely designed to measure a bit fast. In all my years and miles of both car and motorcycle riding, I don't remember ever having a vehicle that was spot-on accurate with a GPS.

    As for your fuel gauge, learn to either calculate the mileage manually (really quite simple) or learn to trust the miles driven. Fuel gauges of most motorcycles, probably due gas tank shape, are pretty useless during the top half of the tank anyway.

    Good luck.
    Royce
    On the coast of Kansas
    2012 F800ST

  6. #6
    Registered User detbmw's Avatar
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    My 1988 K75S speedometer matches my GPS perfectly at 55, at 70, etc.

    Of course, the speedo died a few years back and I had it rebuilt and calibrated at Overseas Speedometer in Austin.
    Rich
    2001 R1150GS, 1988 K75S
    East Texas BMW+ Motorcycle Club
    Texas National Picnic, Jacksonville TX, 3rd Saturday in April

  7. #7
    Speedo issue quite normal on my 07GT and 12GS, a few over what gps tells me.

    Mileage, sometimes it's within .2 gallons, other times it's off 3-4 mpg. I use the trip meter. I know both get 40 or more unless I'm pushing both. Here's something that always made me wonder. Coming back from Ca. I was on cruise at 90 for sometime. Tank should get 240 but pushing it, the computer was telling me I had 27 miles left when the light went on at 140 and change. I limped to the nearest station 40+ miles away [ down to 55 ] and I'd been out according to the computer for about 15 miles. At night on a lonely stretch across the desert, I was not looking forward to walking.

    When I filled the tank, it should have been 6.3 gallons to full, but it only took 5 gallons. I had a gallon left but the computer told me I was dry for some time. 5.3 gallons to make 180 or so miles, still got 33 per gallon. I learned push the GT, and she loves it, it'll gobble the gas. Keep it to 65-70, 42-45 depending on what I'm carrying for luggage.

    What I've come to see on both over time is that when the triangle comes on, I have more than my normal average of 42-45 left. Plenty of time to find a station.
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  8. #8
    slave to gravity skibum69's Avatar
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    My bikes are off by 8-10 km's on the speedo except my 1100S which shows 15 km's off at 200km/h. No fuel gauges on any of my bikes. I was surprised when my crappy Acura MDX was spot on until I put on smaller rims which dropped it to 5 km's low.

    As we're on the topic do you want to tell us the proper way to figure out mileage?
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  9. #9
    Agree with everyone before me.

    Your " fuel strip" will be the biggest problem.
    Learn to use the odometer+ fill your tank to the top each time.
    Conservatively, I fill up at 180 miles each time.
    One up, w min luggage. K1200GT _2008

  10. #10
    Registered User lkraus's Avatar
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    Odometers tend to be more accurate than speedometers, and you can figure your own correction factor by comparing the odometer reading to interstate mile markers over a distance of 10 or more miles. Using a longer distance is better, gives you something to do while crossing Kansas.
    Larry
    2006 R1200RT

  11. #11
    Registered User lkraus's Avatar
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    Quote Originally Posted by brownie0486 View Post
    Speedo issue quite normal on my 07GT and 12GS, a few over what gps tells me.

    Mileage, sometimes it's within .2 gallons, other times it's off 3-4 mpg. I use the trip meter. I know both get 40 or more unless I'm pushing both. Here's something that always made me wonder. Coming back from Ca. I was on cruise at 90 for sometime. Tank should get 240 but pushing it, the computer was telling me I had 27 miles left when the light went on at 140 and change. I limped to the nearest station 40+ miles away [ down to 55 ] and I'd been out according to the computer for about 15 miles. At night on a lonely stretch across the desert, I was not looking forward to walking.

    When I filled the tank, it should have been 6.3 gallons to full, but it only took 5 gallons. I had a gallon left but the computer told me I was dry for some time. 5.3 gallons to make 180 or so miles, still got 33 per gallon. I learned push the GT, and she loves it, it'll gobble the gas. Keep it to 65-70, 42-45 depending on what I'm carrying for luggage.

    What I've come to see on both over time is that when the triangle comes on, I have more than my normal average of 42-45 left. Plenty of time to find a station.
    BMW plans for a "reserve" of about a gallon, so "distance to empty" is really "distance to reserve". I wish the display showed negative numbers, as looking at "---" can be a bit nerve-wracking.
    Larry
    2006 R1200RT

  12. #12
    Left Coast Rider
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    One might ask themselves if they'd prefer a speedo that read high or one that read low - especially in Ohio.

    You: "Honestly officer, I was only going 59 mph."
    Trooper: " Well, I had you at 62 mph. You can appear in court or pay this ticket by mail."


  13. #13
    Quote Originally Posted by BC1100S View Post
    One might ask themselves if they'd prefer a speedo that read high or one that read low - especially in Ohio.

    You: "Honestly officer, I was only going 59 mph."
    Trooper: " Well, I had you at 62 mph. You can appear in court or pay this ticket by mail."

    That is why I always ride with a GPS even when I know where I am going.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  14. #14
    Fortis Fortuna Adiuvat Omega Man's Avatar
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    Quote Originally Posted by PGlaves View Post
    That is why I always ride with a GPS even when I know where I am going.
    Usually the GPS will give the top speed for the trip
    OM
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  15. #15
    not so retired henzilla's Avatar
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    Quote Originally Posted by lkraus View Post
    BMW plans for a "reserve" of about a gallon, so "distance to empty" is really "distance to reserve". I wish the display showed negative numbers, as looking at "---" can be a bit nerve-wracking.
    I have had three Beemers that were spot on... when it said you had three miles, it stalled at 2.7. Two Wedge Ks and a GSA.! My RT ran on zero escaping path of hurricane for around fifty miles as all the stations were closed or overrun. Usually keep topped off but sometimes plans go south.


    Our KTMs start counting up at reserve and can scare you at first glance. Hs 390 only holds 2.5 gallons to start with so really watch mileage on fuel runs with little availability in path.

    The speedo reading faster has been consistently off by around 3 mph on all our various models. Trying to convince folks in a group ride that riding at 5 over the dash is closer to the true speed is a hard sell to some.m
    The gentleman from New Mexico will explain the German reasoning and that only authority models are true calibrated units.
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