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Speedo is out :(

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by FBU, Mar 19, 2008.

  1. Hi Guys,

    Sorry about the n00b question, I am still new to these forums (and bikes, only been riding for a month).

    Anyway, I purchased a 2nd hand Kawasaki ZZR250 and it seems that I am travelling faster than my speedo is indicating. I know this because I have been snapped up by a speed camera whist travelling a couple kilometers "under" the speed limit (so the speedo indicated).

    The only information I have from the previous owner is that the sproket and chain had been replaced (from the search I did I think thats the reason). Anyway, does anybody in sydney know of a mechanical workshop who can check my speedo and confirm its over (I would like to get a letter for legal reasons, incase a fine does come in) and more importantly fix it so that I am not constantly speeding.

    Thanks in advance, any help / comments you guys can offer will be much appreciated.

    (PS, from my search I gather its the sproket size that has done this however I dont know of anybody who can confirm and fix)
  2. An incorrect speedo won't get you out of a speeding fine, and changing sprockets won't affect it's reading (fairly sure the ZZR speedo is driven from the front wheel).
    What you're experiencing is normal for mechanical speedos when they get old, if you want something more accurate do what many people do and fit a bicycle speedo.
  3. Yup, greab a Sigma bike computer. They are easy to setup and work well. I have a BC1606L model.
  4. how much over were you?
  5. If you are doing 8000rpm in top at 100km/h you have standard gearing.
    My gps shows at an indicated 100 our ZZR250 is doing 95.something.

    So how does that sit with you?
  6. Which is what I thought most GPXs and ZZRs do - they indicate a speed that's faster than you're actually doing.
  7. For some reason most bikes are 6 - 10% optimistic. Shouldnt be but they are :mad:

    OP may have non standard sprockets although that would take a fair edge off the ZZR performance :eek:
  8. That's all they need to be to pass ADRs, why would manufacturers bother making them more accurate (and why would the Government change the ADR when they make so much money booking people for being as little as 3% over).
  9. I dont know what the rev range is at 100km/h, however I can tell you that at 60km/h it revs at 5000 (in top gear).

    Would replacing the speedo (by a kawasaki shop) fix it? I find it strange that a 95 model bike has issues with keeping speed, however an 89 model car I have reads speed fine !
  10. I know whare you're coming from jd, but cars (stock) are much more accurate and with electronic speedo's there is no need for a big margin.

    The first thing I do with any new vehicle is check it against my gps :)
  11. Wind it up to 100 (legal) and have a look.
  12. Other than the fact digital speedos were expensive and unreliable around the time the ZZR was first designed. Even now a digital display is still no guarantee of accuracy, those overhead speed checks being a good example, or at least the one on the Western Highway that always reads much LOWER than my speedo and GPS (a cynical person would think that's to make people speed up and get caught by the speed camera that often sets up a few kms further down the road).
  13. Speedo

    Make sure you're running the correct tyre on the front as this will affect the speedo reading.
  14. seriously guy, just because it's digital doesn't mean it's more accurate, even though it appears that way due to the exact number.

    Adding the electrics adds another level of inaccuracies.

    and the road side speed indicators . . .pfft
  15. Negatory, it CAN, as long as you provide a letter from a mechanic saying how much it was out by. BUT you can't get off if you were speeding more than 10%. Ie. if you were doing 88 in an 80 zone you can be let off, but if you were doing 90 in an 80 zone, you can't be let off using this reason.

    zzr250 uses a pickup on the front wheel, so sprocket won't effect it one bit. Tyre type and pressure will effect it, but since it actually reads the other way (ie. when it shows 110 on the speedo you're doing more like 100 real speed), it seems you were probably just speeding.

    If you were just speeding, unless you are really good friends with a mechanic, then you're cooked - as writing in and saying your speedo was off does nothing unless you have it backed up by certified mech.

    Unfortunately getting it testing to see if it was actually off is difficult since it does pick up speedo from the front wheel, meaning a run on the dyno wouldn't help :grin:
  16. Yeah I thought of that on the way home :)
  17. I drove the Geelong section of the Princes Freeway on Sunday. I passed a speed check sign. I compared it to my GPS. The speed check sign was spot on. Car was on cruise, flat road, steady speed, indicated 101 km/h on the GPS. The speed check also indicated 101 km/h.

    Recently there was on of those trailer mounted speed check devices around here. I checked it against the GPS. It too was spot on. I think the older types that were regarded as unreliable were made and maintained by the same mob that did the Western Ring Road cameras, which we all now know were stuffed...

    As for the cycle computer, yep, best way to go. Sigma Sport gets you an accurate speedo and a nifty trip computer in one. Only problem is that they don't illuminate at night. Well, most don't.
  18. The problem with the ones which do have a back light... is they are the wireless version which seems to get interference from my ignition (Gpx250) >_>
    Wish there was a wired one with a light, but even the cheapest of cheap sigma's does the job, was like 20 or 30 dollars, can't remember.
  19. The 1606L is a wired BC with a backlight. But it only comes on for a couple of seconds, much like that of a watch. Sigmasport did make a small LED light that perched over the BC and clamped to the handlebars. Not sure if it still sells it (www.sigmasport.com) but it too would have a finite life.

    I'd like to be able to wire something direct from the bike battery and have it come on with the ignition. But pulling the BC apart would most likely wreck it, just looking at how it's assembled.

    Perhaps if we all started a letter writing campaign to Sigma Sport requesting such features as externally powered backlights and more features for the trip computer component, then maybe SS might consider them for future models.
  20. Say what??

    My speedo indicated that i was doing around about 57 -58 km/h (def under 60) in a 60 zone when the camera went off. According to my speedo I wasnt speeding (not sure if I made this clear in my first post ... I am not trying to get our of a speeding ticket, If I choose to speed, I am happy to take responsibility however I didnt think I was speeding ... I had no indication to assume I was).

    Regading the rev range at 100km/h ... I am on my L plates, so I cant test this.

    Some goo suggestions, I will check the tyre at the front (I believe its some sort of dunlop), will confirm the tyre pressure and look into these digital speedo units. I also spoke to a bike shop yesterday night, they told me to compare my speed next to a mates car an book it in if its out.