Speedo reading excessively high

[anthraxnz]

Hi guys,

I have a 98 RG 150. It came with a digital dash system designed for dirt bikes. I didn't like the fact i didn't have all the warning lights so i put the original dash cluster back on. It turns out the previous owner replaced it for a reason...

So when riding at 50km\h the indicated speed is 60km\h, when riding at 100km\h the reading is 120km\h

Is this a simple fix? From what i can gather it could be one of 3 things: 1 the speedo drive, 2 the speedo cable and 3 the speedo itself.

Are there any techniques or info you guys have about diagnosing\resolving this problem?

Thanks.

[george formby]

Got the same issue with G/F's bike. Fitted a bicycle speedo to get the guts on it. Regardless of gearing the wee $40 thing reads accurately.

[nzspokes]

Got the same issue with G/F's bike. Fitted a bicycle speedo to get the guts on it. Regardless of gearing the wee $40 thing reads accurately.

I do the same on my Hornet. Its a great thing.

Only reads up to 199kph but, they expect cyclists to be slow.

[Jantar]

Over reading is very common on many vehicles. Bikes are usually 8 - 10% out and cars are 5 - 8% out. Your error does seem excessive. The cheapest and most accurate solution is to mount a basic GPS on the handlebars.

[slofox]

Have a lookee here...


http://www.healtech-electronics.com/ Click on "speedohealer."

I bought one of these for the gixxer. Works a treat, although they are bike model specific to some extent.

Probably dearer than a GPS though...

[anthraxnz]

Just had a look at the speedo healer. This bike has a cable speedo so that's probably not going to work...

The site does have a cool calculator, turns out mines out by 16.7% lol

Maybe ill find a way to mount the dirt bike speedo thing.

[Big Dog]

Some speedos of the cable to front wheel variety have an adjustment screw inside the housing. Slow process but. You basically need to disassemble turn the white flat screw one way a quarter turn. Assemble. Test. Repeat.


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[Big Dog]

Obviously you void any warranties and will be breaking the law if it now reads too low. Because this will also affect your odometer.


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[anthraxnz]

Obviously you void any warranties and will be breaking the law if it now reads too low. Because this will also affect your odometer.


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Cool, thanks for that! I'll remove it and see what i can find. Yeah i'm not concerned about the warranty lol, 1998 was so long ago... or am i just getting too old?

[FJRider]

Obviously you void any warranties and will be breaking the law if it now reads too low. Because this will also affect your odometer.




For a WOF ... Speedometers need to work. They do not need to be accurate. And there is no legal requirement for speedometers to be tested for accuracy.

However ... it is up to the vehicle operator to not exceed posted speed limits. How they achieve that is up to them.

And ... I have never heard of excessive speeds voiding any warranties either.

[Big Dog]

Wilfully misrepresenting your mileage may not be a warrant issue but is not legal.


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[Big Dog]

Excessive speed will not void a warantee but opening the housing on any instrument may void one.


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[Akzle]

my speedo frequently reads high. A'cours, i usually gofast.

[BoristheBiter]

my speedo frequently reads high. A'cours, i usually gofast.

Just not on a bike (and no your mother doesn't count).

[FJRider]

Excessive speed will not void a warantee but opening the housing on any instrument may void one.




I doubt if the OP's 98 150 is still under warranty ... and if a bike you had was ... getting it fixed under warranty would be the logical (and reasonable) thing to do ...

Having a speedometer that reads incorrectly is not "Willfully" misrepresenting the vehicles mileage ... (unless you wind back the numbers claiming innocence). Any illegality in such matters have more impact on dealers/importers .. rather than on Joe Public.

The odometers often reads (almost) correctly ... even if the speed indicated is NOT ...

[Akzle]

little hoop on der frunt?

[anthraxnz]

so i pulled the speedo apart and it appears there no screw to calibrate it.

I thought the tyres might be part of the problem.

Factory sticker says:
Front: 90/90/17 45S
Rear: 110/90/17 60S

Current Tyres:
Front: 120/80/17
Rear: 120/80/17

Would this change throw the speedo off by 16.7%?

[Mike.Gayner]

By my calculation that only puts it out by about 5%.

edit: And would make the speedo under-read, not over-read.

[Asher]

Same width front rim?
While the tyre has gone down in profile the increase in width to 120 will force the profile up quite a lot. This will probably be causing the readings

Edit: actually that should make it under read, not over read.....

[nzspokes]

http://www.bikebarn.co.nz/echowell-u10-wireless-10-function-computer.html

Mines been going for about 30,000ks on different bikes.

[george formby]

http://www.bikebarn.co.nz/echowell-u10-wireless-10-function-computer.html

Mines been going for about 30,000ks on different bikes.

How do you get the magnet close enough to the sensor? The gap on mine has to be <5mm. PITA

[anthraxnz]

I found this calculator: http://tire-size-conversion.com/speedometer-calibration/

Seems to be in the right area when i punch the differences in.

@100km\h i should get 127km\h on the clock which is about right. I see 120.

Pretty sure this is the problem. Thanks for all your help :)


ps i had to convert it from MPH to KM\h

[leathel]

I found this calculator: http://tire-size-conversion.com/speedometer-calibration/

Seems to be in the right area when i punch the differences in.

@100km\h i should get 127km\h on the clock which is about right. I see 120.

Pretty sure this is the problem. Thanks for all your help :)


ps i had to convert it from MPH to KM\h


That site didn't work correct for me.... you could enter all sorts of profile and it wouldn't change, change the width and it would?

Bike tyre is width x % = height

120x80% = 96

90 x 90% = 81 profile the smaller the profile the faster it reads

so unless you got the factory & actual around the wrong way above it should be reading slow :blink:

[Akzle]

That site didn't work correct for me.... you could enter all sorts of profile and it wouldn't change, change the width and it would?

Bike tyre is width x % = height

120x80% = 96

90 x 90% = 81 profile the smaller the profile the faster it reads

so unless you got the factory & actual around the wrong way above it should be reading slow :blink:

rim width. Different from tyre width.

[nzspokes]

How do you get the magnet close enough to the sensor? The gap on mine has to be <5mm. PITA

Old magnet with double sided tape on the rim. Sensor on fork leg. Easy.

[anthraxnz]

That site didn't work correct for me.... you could enter all sorts of profile and it wouldn't change, change the width and it would?

Bike tyre is width x % = height

120x80% = 96

90 x 90% = 81 profile the smaller the profile the faster it reads

so unless you got the factory & actual around the wrong way above it should be reading slow :blink:

sorry i typed the front tyre in wrong. its 100 not 120

[FJRider]

The question is ... how long has the issue existed .. ??? :corn:

Since the OP "Noticed" it .. ?? ;)

Or .. since it left the factory .. ??? :pinch:

A little arrow sticker on the speedo dial at all speed limit (actual as opposed to indicated) points and no worries. :yawn:


Too easy ... ??? :innocent:

[leathel]

sorry i typed the front tyre in wrong. its 100 not 120


in that case they are pretty much the same actual height..

put a 19" wheel on the front :P

[george formby]

Old magnet with double sided tape on the rim. Sensor on fork leg. Easy.

Ah, on ze rim! I've used 19 cat stranglers & a bit of alkathene pipe to stick it on ze spoke. 2 pearls of wisdom from KB & it's only 9:30. Grouse!

[clint640]

Your error does seem excessive. .

Not for a 150, every one I've met over-read the speed to a hilarious degree. I'd go with the wee sticker on the speedo solution, borrow a gps to calibrate it.

Cheers
Clint

[LiamBirkett]

I have the same bike as you and my speedo is also out. Its because the previous owner put a funny size tire on. You could pay a dude to put some new cogs and shit in but its about $100 from memory. I just have got used to seeing the speedo slightly out, and Im allways speeding so it doesn't matter anyway.

[FJRider]

I have the same bike as you and my speedo is also out.

Perhaps ... it's a common problem with that model ... <_<


Its because the previous owner put a funny size tire on. You could pay a dude to put some new cogs and shit in but its about $100 from memory.

You have a bad memory ... or ... you have no fucking idea. :facepalm:

It would be unlikely (or lucky) to have the correct cog ratios fitted (or actually available) to make it run true to actual speed on the speedo. :yawn:


I just have got used to seeing the speedo slightly out, and Im allways speeding so it doesn't matter anyway.

Knowing how much the speedo IS out in the various speed zones IS important.

The responsibility is on the vehicle operator to maintain legal speeds.

An accurate speedometer is NOT required by legislation. It is just required to WORK ..