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Speedo and odo out

Discussion in 'Technical and Troubleshooting Torque' started by HeavyNinja, Apr 13, 2016.

  1. hey guys, what would cause my speedo to be out? Each person I have ridden with has said I am at least 10% out when compared to their speedo, and not on the slow side of out. This means I have to be super vigilant about it during my practical. After I guess it isn't too much of an issue until I get on the hwy, but what would cause it to be out by so much. It is out also on the odo. We did a run which I registered at 150km, the other person got 161km from petrol station to station and I know we did more than 150km as I drive the roads all the time.

    It had a brand new set of dunlop arrowmax put on before I purchased it, not sure if they have changed the wheel diameter
  2. Yes, change of wheel diameter can do it, tyres with different profiles, change of sprocket size can also do it if you have changed to go up or down a tooth. You may need to invest in a Speedo Healer. Or a cheaper option is to get a speed App on your mobile phone and some enamel white paint and mark the outside of the speedo (assuming it is a analog display speedo) on the major traffic speeds, 20, 40, 60, 80, 100 comparing it against the phone app to get your points.
    • Like Like x 3
    • Agree Agree x 2
  3. Thanks Chris. Changed my sprockets last week and the speedo is now worthless. Just bought a speedo healer today (y)
    • Like Like x 1
  4. I am thinking the sproket is stock as it will do 110 with me on it at 7k and that little fuel economy light is on.
  5. The sprockets have numbers on them that tell you how many teeth they have. Check them out against what the specs say to be sure.
    • Like Like x 1
  6. No probs, I printed off a manual for it so will have a look when home.
  7. does your bike read speedo from front wheel, rear wheel, or gearbox/ECU?
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  9. That was excruciating o_O
    • Agree Agree x 1
  10. She must work as Donald Trump's campaign manager.
    • Funny Funny x 1
  11. Lets see if I've go this right - when your speedo says your doing 100 your actually doing 110? or is it the other way around?
  12. HeavyNinjaHeavyNinja i remember you saying you've got a 48T rear sprocket up from 42? The will give you more acceleration but less top speed. Which means when the back wheel is turning at whatever rotations it does to make the speedo read 110 (or your gearbox, or whatever your bike is using to measure the speed), you're actually doing less distance and hence going slower than that.

    Speedo healer is the solution if you're messing around with the sprockets. There's a mobile app you can get where you put in your bike model and stock sprockets and chain links, then change info accordingly (ie -1 teeth in front, +6 teeth on the back, +1 chain link or whatever) and it'll tell you how to program the speedo healer to give you correct readings. You just unplug the speedo cable and throw the healer in series and away you go.
    • Like Like x 1
  13. I thought motorcycle speedometers were reading wheel revolutions?
    Changing sprockets shouldn't make any difference should it?
    I'd say it's more likely the change of tyres caused it, the new tyres might be taller (larger rolling radius) than the old ones.
  14. Not always.
    Quite a few calculate speed from gear ratio and RPM.
    • Informative Informative x 1
  15. As above, can be read from front wheel, rear wheel or gearbox/ECU. If from gearbox or ECU, that's before your rear sprocket and the road, so any changes in the rear sprocket will affect your speed without actually affecting your speedo.
  16. It seems it has a 42T which is stock. I can see a bunch of numbers but ended in 42T someone told me it was 48. I am about to head out with the gps on and test. Will go no faster than 60 and then check my max speed on my phone when home. I know at 110 I catch everyone, but I did $1.64/5 yesterday (would barely go faster) and gos showed max was $1.65, I thought max was $1.75 as there was a spike there but gps said max was what it was. So not sure it is out, maybe it is spot on and as cars are inherently built 10% slower I catch everyone. Except bikes were telling me I was out.
  17. FWIW, my Yamaha XJ6's speedo was/is fairly lavishly out too. When riding at an indicated 110 km/h, everyone seemed to gain on me. Measured against a car speedo indicating 110 km/h (which in turn had been tested against GPS and found to be within 1-2 km/h), mine read 118 km/h. I've heard anecdotally that quite a few motorcycle speedometers can read up to 10% higher than actual speed.
  18. ^^ Yup, my VStrom is 5-6km higher over all speeds and the DR seems to be about 10% higher.
  19. My speedo never goes above the speed limit....
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    • Funny Funny x 2
  20. Well it is not 10% out. I prob hit 85 and gos says 89.1