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speedo out? Headlight

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by splitty, Feb 2, 2008.

  1. Hi being a newbie i will apolagise up front for asking too many dumb ?s I have 98 cbr600f went for my first long ride to-day i was trying to stay on the speed limit but everyone was passing me like i was going too slow?in 100k zones i was sitting just over the limit ? same in 110 zones? also could someone tell me with my bike should the headlight come on when i turn the key on or when i start the motor :?:


     
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  2. Cant help with the headlight although I suspect it comes on when the key is in the "on" position.

    Dont be surprised if your speedo is 7 - 10% fast even with standard gearing. Check it against a GPS then you'll know.
     
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  3. +1
    and ifyou dont have access to a gps, use one of those 5km stretches on the highways marked with "check your odometer here"
    zero the trip meter and measure it whilst riding.
    if, for example you get to the 5km post and your trip meter reads 5.4km your speedo error is 8% over or, you are doing 100km/h at an indicated 108 on your speedo.
    to work it out mathematically, it is-
    ((a-b)/b)x100 = c
    a= your measured distance
    b= the posted distance
    c= speedo error (could be a positive or negative number)
    :grin:
     
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  4. speedo?

    thanks i will try the speedo check on the freeway to-morrow :)
     
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  5. That's a reasonable assumption, but it does not necessarily correspond in real life.

    Our Peugeot odometer reads about 2% under according to the RTA measured 5 km, while the speedo reads about 2% fast, calibrated with the GPS.

    While the input drive is the same for both, the odometer has fixed gearing, but the speedo uses (if it is a dial-type device) a magnetic mechanism to move the needle around.

    Digital speedos should be the same as their matching odometer.

    Our NSR150 reads 15 kmh fast at 110 kmh. Silly me has not checked it against the fabulous measured 5 km, because the nearest one is 60 km away. Then again, I could just check it against the Peugeot.

    Cheers

    Trevor G
     
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  6. Until you asked that I thought all bikes (that the light automatically comes on) had the headlight start when the engine kicked into life - even if that "kick" isn't enough to start the engine properly...
    Now I'm wondering if that's the same with all bikes :?
     
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  7. Every bike i've payed any attention to, has the headlight on with Ignition, eg: When the key is turned to the 'ON' position.
     
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  8. what is the tolerance for the gps? +/- 2% with the best of the best gear from memory ;)
    stop nitpickin'!
     
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  9. That will only check his odo. The speedo accuracy can vary greatly compared to the odo.

    For example, my Blackbird's odometer reads about 10km over on a 400km ride. But the speedo can vary by 5-20km/h depending on the speed.

    I bought and calibrated a Sigmasports cycle computer against a GPS and use this regularly to compare speedo/odometer readings.
     
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  10. of course, the difference is a percentage of your actual speed. the speed sensor delivers information to both your odo and your speedo. and if it is a bike with a gear style pickup that too controls both your speedo and odo.
    trevor is correct, the needle type speedo is controlled by a magnetic setup, which is controlled by the frequency at which the ecu receives pulses from the speed sensor. much the same as how your cycle computer works. it generates an electronic pulse via a magnet and pickup and then depending on your calibration, delivers a result. the cycle computer is only as accurate as the day you calibrated it with regard to your tyre wear.
    in my work vehicle, i have a digital flow meter setup to measure distances, and according to RTA specs it has to be within +/- 0.5% to measure jobs etc. (eg. i quote/charge them per square metre, and believe me, every one counts) i have to calibrate weekly. it measures to 0.01 of a metre whilst driving and displays a road speed indicated in metres per second. you would be amazed at how much the accuracy of your odo can change with just a weeks wear on the tyres.

    the only thing that could make your odo and speedo not run with each other (specifically on your blackbird) is a voltage drop, short, or excessive resistance in the speedo control IC which makes it count pulses incorrectly.

    edit- also, the common ic used in these setups is a 555 which is a very primitive clock-style timer and is only accurate itself up to a certain frequency. so, once you start getting to a squillion pulses/second, your error increases drastically. but we are talking 300km/h now...

    the pleasure was all mine.
     
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  11. My Garmin 12XL is accurate to .1% (point 1) with 4 or more birds up.
    Close enough for me as far as speed goes. Not bothered with odo side.
     
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  12. 1) Never thought of you as a "nit". ;-)

    2) GPS is unerringly accurate: have the americans ever failed to hit an Iraqi kindergarten or hospital when they needed to?

    3) It is not accuracy which comes into play when measuring speed or distance on a GPS, but resolution.

    GPS is rated at +/- 5m, although farmers see about 1.0m I believe.

    Resolution, on the other hand, is the distance you have to move before the display/readout updates with new coordinates, or registers movement.

    In practise, resolution is around 0.5 to 1.0 m. I'm not sure where your "2%" comes from.

    4) Altitude is the GPS weak point. At best it gives a good approximation and I guess that is why every now and then a smart bomb will pass over the school or residential estate and actually hit a petrol refinery or chemical plant in the background, causing massive explosions and release of toxicity that kills innocent people nearby.

    All the best

    Trevor G
     
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  13. so before a speed is even calculated, there is an error of 1%.

    also, look here
     
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  14. Glad we havnt mentioned apex's Joel :eek: :LOL: :LOL:
     
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  15. :oops: :bolt:
     
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  16. Still doesn't address the issue of how an odometer's accuracy can differ from that of the speedo, particularly with mechanical driven units and those that are electronic but have mechanical parts, such as an analog speedo.

    ie. Riding 5 clicks will only confirm the accuracy or otherwise of his odometer. His speedo may read high or low, regardless of what the odometer reads.

    If it's all electronic, then yeah, you'd reckon that the speedo and odo should have the same accuracy.

    A chap named "Nev.." said in another forum (I think it was) that when he fitted his speedo healer to his Blackbird, while the speedo read accurately the odometer's accuracy changed from readin about right to reading low, which is OK for him I s'pose. Fewer kays clocked up...


    Undoubtedly.
     
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  17. Can anyone else confirm that most bikes are like that? So most people are starting their bike with the headlight already on? Why on earth would they make such a power drain while starting? That doesn't sound right...
     
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  18. Because modern, hi quality starters can handle it. Some will kill the lights during start. Others won't. Don't worry about it. :)

    Cheers

    TG
     
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  19. My GPX had a separate switch altogether for the headlight.

    The bandit the light came on when the key was "on" ready to start.

    My ZX6R the headlight doesnt come on till I start the bike (it auto turns on after its started, when its NOT started it isnt on).
     
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  20. On our ZZR250 and the Bandit 1250 the headlight comes on when ignition is in the "on" position. On both bikes the headlight is automatically OFF while cranking activated by the statrer button. When the button is released the light is on again.

    On my old RF900R The light was on and stayed on while cranking but it never was an issue. You're not talking about crappy old english 6V +earth stuff. Modern engines fire quite quickly and current electrics are desinged well.
     
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