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Thread: "1997 R1100RT is too slow"

  1. #1
    Registered User dieselyoda's Avatar
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    "1997 R1100RT is too slow"

    I thought that might get some attention. I love this forum. There are some awesome ideas and some pretty out of this world, complicated responses to simple problems.

    I don't fix Beamers for a living so I don't feel guilty looking for answers here and not paying for the expertise. I think if you are a for-hire wrench and grabbing the great info available here, you should be paying a subscription, just like I do for Mitchell or Alldata.

    My buddy and I went for a boo this morning with some of those noisy twin guys. Lovely day but he complained he was "up" there in the speedo to keep up. Really, we weren't crazy fast, a few sixty's but most were fifty.

    We swapped bikes and I threw my GPS on it. WOW!! He was 8 MPH slower than the speedo indication. I checked the tire size, bang on, tire pressure, perfect. I took the cable out at the drive end, free. The speedo drive was turning freely....................

    Couple things pop to mind, the speedo head is wildly inaccurate or it's from another oilhead with different size front tire. Here comes the questions:

    Do the various oilhead models come with different front wheel diameters? Aspect ratio won't make that much difference.

    Is there an adjustment or a calibration method for the speedo head? Who could do that?

    I would doubt the drive could read too fast, slow I could see if it had a tooth or three missing. is it possible to have different speedo drives for different models?
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

  2. #2
    Survivor akbeemer's Avatar
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    This is an excerpt from a 2002 Service Bulletin:

    The maximum amount of speedometer advance is 10% of the vehicle’?s actual speed plus 2.4 mph.
    Actual speed=55 mph 55 x 10% = 5.5mph; 5.5 mph + 2.4 mph = 7.9 mph. Permissible displayed speed is from 55 to 62.5 mph.

    The displayed speed must never be less than the actual speed. No repairs or replacement should be attempted if the speedometer advance is within 10% plus 2.4 mph

    Not sure this addresses your issue.
    Kevin Huddy
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  3. #3
    Registered User dieselyoda's Avatar
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    Really, asked and answered, now we can do some math.........

    Quote Originally Posted by akbeemer View Post
    This is an excerpt from a 2002 Service Bulletin:

    The maximum amount of speedometer advance is 10% of the vehicle’?s actual speed plus 2.4 mph.
    Actual speed=55 mph 55 x 10% = 5.5mph; 5.5 mph + 2.4 mph = 7.9 mph. Permissible displayed speed is from 55 to 62.5 mph.

    The displayed speed must never be less than the actual speed. No repairs or replacement should be attempted if the speedometer advance is within 10% plus 2.4 mph

    Not sure this addresses your issue.
    7.9 is close enough to the 8 I got.

    If the speedometer is over-reporting, that means the odometer is as well. That means tire mileage is under-reported, fuel economy using the odometer isn't close at all. Best implication, think about warranty. If you were denied warranty being over mileage, you might have paid a bill that you didn't need to.

    Shades of the Honda fiasco here.

    Makes me happy that I didn't worry about wideband O2 sensors and all the crap about coding plugs.

    Makes me kinda sad though, when I thought I was going really fast, I was just going sorta fast.

    Then again, if I look for another Beamer, I won't worry about the odometer reading so much. I think I'll leave my GPS at home too.

    Since we had such a nice day and you ride to have fun and we did and pay way too much for a couple cold ones, it doesn't really matter that much.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

  4. #4
    Cannonball Rider #52 darrylri's Avatar
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    Just because the speedo reports high, doesn't necessarily mean that the odo is off, too. They run from a common cable, but after that, they are different mechanisms.

    The speedo works by spinning a magnet inside a steel cup, which is held by a light clockwork spring. The magnet tries to drag the cup along and the spring resists. As the magnet goes faster, it drags the cup along further in its arc. This system can be set to show any kind of reading for a given number of magnet rpm.

    The odo has a small gear train that counts the exact number of revolutions the cable makes; it doesn't care how fast that happens.

    The bulletin quoted above implies that BMW knows the speedometers are optimistic, and that they are that way on purpose. BMW does not want to be on the receiving end of a lawsuit because the speedo lied to you and you got a ticket (or worse, had an accident). BMW speedos have been renowned for their optimism since the 1970s.
    --Darryl Richman, forum liaison
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  5. #5
    Registered User dieselyoda's Avatar
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    Quote Originally Posted by darrylri View Post
    The bulletin quoted above implies that BMW knows the speedometers are optimistic, and that they are that way on purpose. BMW does not want to be on the receiving end of a lawsuit because the speedo lied to you and you got a ticket (or worse, had an accident). BMW speedos have been renowned for their optimism since the 1970s.
    I don't want to sound like a smartass darrylrj. I know exactly how a speedo/odo works. I just wanted to create a discussion about how simple problems on this forum can turn into complicated, mind blowing discussions that can last for weeks.

    Akbbeemer's comments was certainly an eye opener, as are yours. They still have nothing to do with the simple fact that BMW purposely built an inaccurate system. I doubt we would tolerate that on our bread winner machines.

    To inherently create a mechanism to reduce liability by the manufacturer on something as critical as accurate speed relationships discredits the owners as being idiots.

    Still not trying to sound like a smartass with 35 years on the tools, I never had that problem with my thumpers and airheads.

    That last sentence made me sound like a smartass, sorry.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

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    Registered User R100RTurbo's Avatar
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    Here's what I tried on my lazy airhead speedo (acts like an oilhead so some latitude sought out here although also cable driven, gears within). I had my son drive trusty car beside me one afternoon at predetermined speeds for reference while I took careful stock of various speeds. Turns out there was a general trend/ error of about 12kph over a range of higher readings, with bike having stock equipment/ ratios/ tires/ etc where it counts.
    Simple analog procedure was to remove the needle and rotate back that 12kph difference to gain an average improvement overal, the gauges come apart easily enough.
    Close enough now I don't pay much attention anymore.

  7. #7
    Registered User dieselyoda's Avatar
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    Quote Originally Posted by R100RTurbo View Post
    Here's what I tried on my lazy airhead speedo (acts like an oilhead so some latitude sought out here although also cable driven, gears within). I had my son drive trusty car beside me one afternoon at predetermined speeds for reference while I took careful stock of various speeds. Turns out there was a general trend/ error of about 12kph over a range of higher readings, with bike having stock equipment/ ratios/ tires/ etc where it counts.
    Simple analog procedure was to remove the needle and rotate back that 12kph difference to gain an average improvement overal, the gauges come apart easily enough.
    Close enough now I don't pay much attention anymore.
    That's too simple for words...................................
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

  8. #8
    RD'nNH&AZ rdhudson's Avatar
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    Worked on my airhead too

    I to had a 10mph error on my airhead (R80RT) that read too high (60 mph shown at a speed of 50). Then the odometer quit so I pulled it and superglued the offending gear on the odometer's shaft on the advice and help of a friend. At the same time I removed the needle and "adjusted" it back (more spring tension) to get it right on. GPS on the tank to confirm. Actually it required three adjustments to get it spot on at 60mph but that makes it sound harder than it was. I don't know what the R11's speedo's look like inside but I would attempt it in a minute if it took me all afternoon.
    2002 F650GS, 1998 R1100R 75th anniversary edition, 1983 R80RT (just sold), 1959 R60 (in restoration), Honda CT90
    If you must make a mistake, make a new one each time.

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    Quote Originally Posted by darrylri View Post
    The bulletin quoted above implies that BMW knows the speedometers are optimistic, and that they are that way on purpose. BMW does not want to be on the receiving end of a lawsuit because the speedo lied to you and you got a ticket (or worse, had an accident). BMW speedos have been renowned for their optimism since the 1970s.
    Part of it is, becasue it is a law in Germany, that speedometers can not "under-report". An officially "calibrated" speed indication device must have an error of -0/+4 %

  10. #10
    Cannonball Rider #52 darrylri's Avatar
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    The RT-P speedometers are reputed to be very accurate (so the cop will know how fast you are going when he writes you up). You can also take your speedometer to a shop and have it calibrated. North Hollywood Speedometer and Overseas Speedometer (Google them) have very good reputations.

    "To inherently create a mechanism to reduce liability by the manufacturer on something as critical as accurate speed relationships discredits the owners as being idiots."
    --Dieselyoda

    Ahh... well, what can I say to that? It's good marketing: it keeps you safer in the eyes of the law and strokes your ego because you think you're going faster than you are.

    Anyway, the speedos on my pre-1970s bikes were all pretty accurate, and they use the same mechanism. The newer ones can be made to be just as accurate, but that's not what BMW specified for them, from the factory. This is not news, and it's not just BMW. Magazine test reports have long noted optimistic speedometers on bikes of all stripes.

    BTW, measuring your bike's speedo against your car's speedo isn't necessarily going to be that accurate. Cars are subject to the same legal requirements as bikes. Use a GPS (while going in a straight line) if you really want to know.
    --Darryl Richman, forum liaison
    http://darryl.crafty-fox.com

  11. #11
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    Quote Originally Posted by darrylri View Post
    . This is not news, and it's not just BMW. Magazine test reports have long noted optimistic speedometers on bikes of all stripes.

    .
    BMW speedos, unfortunately, are among the "fastest" ones. Harley Davidson and Ducati (supposedly) are the best ones as far as accuracy, according to Motorcycle Consumer News a while ago ( Have to find the article)

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    Quote Originally Posted by Dieselyoda View Post
    I To inherently create a mechanism to reduce liability by the manufacturer on something as critical as accurate speed relationships discredits the owners as being idiots.

    .
    Anything man-made can never be 100% accurate when mass produced. The more accurate it becomes, the more expensive it will be. Look at watches. ( I know, I know, you have a cheap quartz watch which is dead accurate...)
    If you want to control the error of the item you make and remain within the legal limits -if there are any - you must put a safe tolerance into your process. In this case, it is all on the fast side, because the law doesn't allow to err on the slow side. Of course, they could make a speedo just for the U.S., I guess.

    And as far as liability is concerned, please answer this honestly:

    You ride on your BMW through a school zone with a 25 mph speed limit. You are going 27 mph according to your speedo and you are being stopped by a cop who will issue a ticket, because he clocked you at 33 mph.
    Your are not going to complain to the dealer you bought the bike from or BMW for causing you to get a ticket?

  13. #13
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    Can I blather in as well? It surprises me that riders get so wrapped up in speedometer accuracy, when for decades many motorcycle speedos tend to be a good 5 to 10% "off". Most in my experience indicate a higher speed than the actual vehicle speed.

    To me, ok, big deal. Works kinda like an automatic "speed check". On my 94 RS I know 65 mph indicated is actually about 60 mph real speed. Same for 75 indicated. For many years I'll ride down the highway at an indicated 65 in an 55 posted area, and never even get a glimpse from an officer.

    I have also checked the odometer against the mile markers on the highways and it is much more accurate. Checked the speedo against the mile markers based on time and found it agrees with my speed indicated about 5-over actual.

    On BMWs with cable driven speedos its just the nature of the bike. If the BMW has an electronic speedo, then I'd expect it to be very accurate. Heck on the older BMW's if you want speed accuracy, buy an electonic speedo for a bicycle and mount that on your bike. Once calibrated to the tire size they are very accurate. Ride more, fret about speedos less.

  14. #14
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    [QUOTE=ANDYVH;892562] If the BMW has an electronic speedo, then I'd expect it to be very accurate. QUOTE]

    your expectations in that case would not be well met.

    The R11S uses an electronic pickup at rear hub. Mine reads high by nearly 10%. Speedo seems to read high by about 1% (based on "measured miles" on the I-state. Gotta do something with your brain thru those endless cornfields of the mid-west, right?)
    Ride Safe, Ride Lots

  15. #15
    Day Dreaming ... happy wanderer's Avatar
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    Quote Originally Posted by EMSimon View Post
    Anything man-made can never be 100% accurate when mass produced. The more accurate it becomes, the more expensive it will be. Look at watches. ( I know, I know, you have a cheap quartz watch which is dead accurate...)
    I would disagree or at least question that statement. The authorities (Police) speedometer for an RT is exactly the same cost and the civilian one. $189 at MAXBMW. The former is bang on accurate for obvious reasons and the latter is not. Both are mass produced.

    Tuning forks are accurate and mass produced. _Many_ things are both accurate and mass produced. The accuracy of our speedometers is more likely to do with liability than cost.
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

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