Speedo not running true...

[crashe]

I have just been told that my speedo must be out.

When coming back from Hamilton yesterday, both Feint and Limmy have just said that I was going well over the speed limit... yet my speedo said I was doing 120km.
Yes I know, that is well over the speed limit but they say I was doing 140 +

Now I am really shocked at this.... as I do normally stay at around 100 to 110km on the motorway.

So where would one go to get the speedo checked and what would it cost to do this...

Do speedo's go out of sync like this often??????

I am not in any great hurry to get it done.... as the bike will be in the gargage for 2 months on Thursday night. But to get this info now will be of great help for when I am back up and riding again.

Thanks in advance.

[Jeremy]

It looks like you've managed to get a speedo that might actually be showing the real speed. Most bike speedos are out by about 5 - 10km/h at 50km/h. It can get worse the faster you go. Mainly it's done by the manufacturers so you don't break the speed limit.

[jazbug5]

Wrong way round, I think.

[pyrocam]

Try going to one of the AA service centres or VTNZ places with those rolling wheels in the ground that you stick the back wheel on. Ive been tempted to do it myself but havent had time yet.

If you approach the right person and be really nice to them they might do it for free. Im talking about the guys on the floor not the office workers. it would only take a second.

I thought my bike's speedo was overestimating untill I got pulled over at 88 and it felt like I was doing mybe 75. wasnt checking it

[Zed]

I have just been told that my speedo must be out.

When coming back from Hamilton yesterday, both Feint and Limmy have just said that I was going well over the speed limit... yet my speedo said I was doing 120km.
Yes I know, that is well over the speed limit but they say I was doing 140 +

I think the boys (Feint & Limmy) must have eaten too much Burger King??

1. If you rarely exceed the speed limit I'd find it hard to believe that you were doing 140kmph without noticing!
2. I know that speedos are calibrated to show a 'faster' speed than the actual, but I've never heard of one showing 20kmph slower...if the boys are correct then there may be a fault and you will need to have the speedo recalibrated or repaired/replaced professionally.

2 months is a long break from two wheels, I hope you make it through with few side effects!

[Zed]

Try going to one of the AA service centres or VTNZ places with those rolling wheels in the ground that you stick the back wheel on. Ive been tempted to do it myself but havent had time yet.

I think you'll find that those "rolling wheels in the ground" are for testing brakes not speedometer calibration! Might work on the Virago though?

[crashe]

I think you'll find that those "rolling wheels in the ground" are for testing brakes not speedometer calibration! Might work on the Virago though?

AHEM, you cheeky buggar... lol.

[N4CR]

YES! crashe.. the 1st KB ride I went on (noob ride to wellsford) you stuck at 140 the whole time!... I think you are right about it being out.

[bugjuice]

when you stick a vehicle on a dyno, doesn't that show true speed? There's a few places around that dyno bikes, may be give them a call and find out.

I'm interested in getting mine done too, so if/when you do find out, let us know

[F5 Dave]

when you stick a vehicle on a dyno, doesn't that show true speed? There's a few places around that dyno bikes, may be give them a call and find out.

I'm interested in getting mine done too, so if/when you do find out, let us know

Yeah the dyno should show the true speed (if it is a decent one) But this will only work on the back wheel. Older bikes have the gear drive for the speedo on the front. Only recent bikes with electronic pickup this will work on. Changing tyres or gearing will mess this up too.

A speedo healer will allow you to adjust this error on electronic units. Costs ~ $130Aus. Dunno if avail in NZ, Google one up.

Old world instrument technicians can fix mechanical instruments. Good luck finding one.

[Jantar]

Fit a hand held GPS unit to your handle bars (cable ties will hold it in place) and just ride. You'll soon see how your speedo compares to true speed.

[pyrocam]

I think you'll find that those "rolling wheels in the ground" are for testing brakes not speedometer calibration! Might work on the Virago though?

yes I know they are, but I think they have a speedometer to measure how fast your going next to it. didnt get a close look but it appeared to be one.

*edit. now that I think about it. Im proberly wrong. Ive only seen one once at the Kingsland one. It looks like one but could be anthing with a gauge on it I suppose

the GPS is a good idea but expensive if you dont know someone with one. Originally I was going to get someone with a car to race me along the straight on the 22 with my cellphone handsfree going in the helmet to communicate speeds, but thats kinda stupid.

[bugjuice]

Yeah the dyno should show the true speed (if it is a decent one) But this will only work on the back wheel. Older bikes have the gear drive for the speedo on the front. Only recent bikes with electronic pickup this will work on. Changing tyres or gearing will mess this up too.

A speedo healer will allow you to adjust this error on electronic units. Costs ~ $130Aus. Dunno if avail in NZ, Google one up.

Old world instrument technicians can fix mechanical instruments. Good luck finding one.

most bikes are running off the gearbox now. most newer bikes do, fewer and fewer are running off the front wheel, but doesn't mean you can bodge something together by sticking the front wheel on the rollers, then the back wheel of another bike next to it or something.. Depends on how keen you are to get it working I guess!! Do those rollers have no motors in them at all? Can't see why they would, but I've seen weirder..

Even new tyres compared to old tyres on the same bike can make a difference, but not a heap. The calibration will show the biggest difference, then everything else is a minor adjustment, unless you start playing with gearing and sprockets

[Mr Skid]

Yeah the dyno should show the true speed (if it is a decent one) But this will only work on the back wheel. Older bikes have the gear drive for the speedo on the front. Only recent bikes with electronic pickup this will work on. Changing tyres or gearing will mess this up too.

I understand that in the case of front wheel driven speedos, if the rollers are wide enough, you can put the front wheel of the bike to be tested on the rollers and spin them with the rear wheel of another bike.

[Drunken Monkey]

I could loan you my GPS, or get you to ride along side me for a short stint then we can compare indicated speeds. The GPS is pretty accurate, as long as it's a flat straight road and we hold our speeds for a few seconds for it to do its calculations.
Most brand new cars we've tested are doing 98 when indicating 100.
Most older cars are doing around 90-92 when indicating 100.
The error tends to be a percentage, not a fixed number, i.e. older speedos show 50 when you're doing 46 and show 150 when you're doing err, nah, we'll just flag that one, eh? You get the idea though.
Haven't tested many bikes with it yet.