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Speedometer error

21K views 38 replies 21 participants last post by  jercoupe 
#1 ·
My Majesty speedometer has a 10% + error after passing the 70 kph (45 mph). The dealer even installed a new unit under warranty with no obvious change except that the odometer then read 0 km when it actually had 13 200 on the clock.

This site sells a unit called the "Speedo Healer" which cures this problem.
http://www.speedohealer.com/eng/intro.htm

I hope you find it useful.
 
#2 ·
my speedo is also out by the same type of numbers as yours appears to be.

verified against my gps.
even more proof (if it were needed) is that last week on my way home from work in the evening, i was riding behind one of those new citroen C4's. they have a HUGE digital speedo right in the middle of the dash, it's impossibe to miss seeing, even from behind/beside the car !

it was reading km for km the same as my gps, and my speedo was not matching the other two (the gps, or the citroen's)

jason
 
#3 ·
Why do you think your speedo/odo's would be so far off? The Majesty uses a front wheel sensor, so gearing changes wouldn't affect it. Have you changed tires, perhaps to a different size? Even small changes to the outside tire diameter will change the turns per longer distances/higher speeds significantly. I haven't checked mine, but now I think I'll check my odo against the mile markers.
 
#4 ·
It's fairly common knowlegde that almost all speedos on bikes/scooters are inaccurate. It seems to be a delibrate ploy from the manufacturers of the machines.

They all seem to read about 10 % higher than actual speed.
doesn't seem to matter what brand either.......

jason
 
#5 ·
gpsnut2003 said:
it's fairly como knowlegde that almost all peedos on bikes/scooters are in accurate.it sees o be a delibrate ploy from the manufactures of the machines.

they all seem to read about 10 % higher han actual speed.
doesnt seem to matter what band either.......

jason
Have you been out drinking again? Friends don't let friends post drunk... :lol:
 
#6 ·
lol...

am using a new wireless keyboard. didnt notice that it was missing key strokes till now.....

jason
 
#7 ·
"it's fairly como knowlegde that almost all peedos on bikes/scooters are in accurate.it sees o be a delibrate ploy from the manufactures of the machines."

Finally got a chance to check that theory yesterday. I took my Maj out while a friend rode with me on my old Helix.

When I rode 62-63, the Helix was at 57.
When the Helix rode 62, the Maj was at 69.

So this disproved for me the thought that all bikes read fast to the same degree. It also meant that top speed for the Helix (about 72) is around 80 on the Maj! That's a bit of a disappointment because one of the reasons I bought the Majesty was so I could ride faster more comfortably. While it's certainly true that the Maj is faster, so far it (or I) doesn't seem that happy cruising in the 80's.

b
t
 
#8 ·
Eri3c said:
Why do you think your speedo/odo's would be so far off? The Majesty uses a front wheel sensor, so gearing changes wouldn't affect it. Have you changed tires, perhaps to a different size? Even small changes to the outside tire diameter will change the turns per longer distances/higher speeds significantly. I haven't checked mine, but now I think I'll check my odo against the mile markers.
Checking your odo against mile markers will not reveal the speedometer error in your bike. The odo is accurate, the speedo isn't.
 
#9 ·
I think I figured this out, at least to some degree. The speed and odo are calculated based on the wheel/tire circumfrence. The speed sensor just detects wheel revolutions. Unlike a car, a motorcycle has a curved tire profile, and tilts in turns and curves. So, when riding around a curve, the contact patch is off the center of the tire, closer to the wheel's axis of rotation, effectively reducing the circumfrence of the used part of the tire. Thus, the wheel has to rotate more times to cover the same distance. Since the computer doesn't detect lean angle or account for this variation, it shows a faster speed and more distance traveled around curves. If my theory holds true, the differences should be greatest with a more curved tire profile, more twisties in your route, and a tendancy to take the curves at higher speeds and greater lean angles.

Riding lower profile tires, or underinflated tires would also cause higher readings on the speedo and odo.

For my commute, the bike shows about 2% more distance traveled than a car. Most of my route is on a highway with few straights, lots of curves. It would take a lot of calculations to estimate how much leaning I do, but a 2% difference sounds reasonable given my theory.

Baden, in your Maj/Helix test, was there a difference in speed/lean angles that might account for the indicated speed differences? Does your Maj have original equipment tires?
 
#10 ·
If what you say is true (which it is, but not for the reason you describe) the speedometer would get even more off in turns (which it does). I don't know why bikes have inaccurate speedometers, but since the speedometer is off 10 percent when the bike is upright, it seems to me they hadn't adjusted it correctly from the factory.

Oh well, I know when my bike shows 45 I'm doing 41. To me that's quite a bit off.
 
#11 ·
As far as I know the reason most bike AND auto speedos read higher than the actual speed is for liability reasons. If the speedo read even a tiny percentage LESS than the actual speed then everyone who got a speeding ticket would sue the manufacturer.......
 
#12 ·
if manufacturers purposely mis-calibrate their speedos, then they might as well remove the speedos.

There's also a safety issue with mis-calibrated speedos, as well as anyone who holds their bike to the legal speed of 55 while everyone behind hits their brakes and then accelerate to pass with funny little friendly finger gestures.

The meatcutter took his thumb off the meatscale years ago, it's about time that cycle riders have speedos they can rely upon.

Let me also add that a cyclist going 62mph who is stopped and asked if they know their speed, will incure a ticket for 62mph if honestly answered . . . even though they "know", they were only going 57mph.

I say for $5000+ dollars give me more accuracy.
 
#13 ·
Believe it, the manufacturers mis-calibrate 'em.
A cheap way to get your true speed is to mount a bike computer on your scooter - you can get these for twenty five bucks if you skip the bells and whistles - mount the magnet on the front disc and the sensor on the front fork. Then you have to measure the EXACT distance the wheel travels in two complete revolutions and program it into the computer - this will give you a very accurate speed, and the computers are waterproof and very light.
 
#14 ·
Ishabaka said:
Believe it, the manufacturers mis-calibrate 'em.
A cheap way to get your true speed is to mount a bike computer on your scooter - you can get these for twenty five bucks if you skip the bells and whistles - mount the magnet on the front disc and the sensor on the front fork. Then you have to measure the EXACT distance the wheel travels in two complete revolutions and program it into the computer - this will give you a very accurate speed, and the computers are waterproof and very light.
That's funny... someone posted the same advice on my sportbike forum just a few days ago!
 
#15 ·
And you know those things last. I put one on my mountain bike almost 7 years ago, and it still works and I haven't even changed the battery!! The wire for the sensor has gotten caught in the tire, it's been under water, man you can't kill that thing!
 
#16 ·
Understand these things work, but only give one reading per wheel revolution, whereas your bikes' speedometer may give as many as 80, depending on the model.

I also contacted the speedohealer company. Once installed, the speedometer might be right, but it throws off the odometer, which CANNOT be calibrated separately!!! The odometer and speedo take their readings from the same source, so if you reduce the indicated speed down to an accurate reading you will reduce in indicated mileage down to an inaccurate reading.
 
#17 ·
Certainly there has to be some way of calibrating how many "ticks" (or whatever you want to call the signaling method) are a mile, and how many per second is a mile per hour.

I'm not saying we have access to it, but Yamaha has to have a way. I'm sure it is software based, and I would bet they have a way of adjusting the parameters in the software. I just wish we could get access to it.

I would bet that the main reason we can't get access to it is to limit our ability to screw with the odometer (although a speedohealer does that just fine).
 
#18 ·
I got my information directly from the speedohealer website. There is no way to get into the odometer of the Majesty (legally). The odometer is accurately calibrated, the speedometer is fast. There is only one signal, so if you mess with one, you mess with the other.

I'll just say below 35 its accurate, above 40 add 5mph for actual speed. Good enough for me.

So, no, Chris, AFAIK and as far as speedohealer knows, there is no way to calibrate it since it's electronic other than using their device, which can only make one or the other accurate, not both.
 
#19 ·
What I meant was that somewhere in the internal workings (i.e. computer) of the bike, there is something that decides how the signaling is interpreted for the odometer and the speedometer.

I'm sure only one signal is sent to the computer, but would bet that there are two seperate functions in the computer interpreting the same signal - one for miles traveled, one for speed of travel.

I'm also sure we don't have access to the parameters used in those functions, but I'm fairly certain that Yamaha does. Maybe not through the standard diagnostic software, and maybe not easily, but I would bet if we had full knowledge of the software used (as Yamaha does), it could be corrected, possibly even on a bike by bike basis.

But no, I don't think we will ever get access to what we would need to know to reset the speedometer software parameters (and possibly not the tools to access that software either) - so we won't have a legal way to fix it (and playing around with the software might be considered illegal, too. I don't know).
 
#20 ·
There's no good excuse for a speedometer mis-calibrated by 5-6mph.

IF the manufacturers want to make a speedometer read 1mph more than actual, I'm sure the complaints would disappear and I do not beleive that anyone sues the manufacturer for a speeding ticket within the 5-6 mph, since 5-6 over the speed is a minor offense.

ALSO . . . it's not smart to get cyclist to go 50 to achieve an actual speed of 55, when at the lower speeds the speedometer runs true. SO . . . go 25 in a school zone and you become an unsafe operator.

PLAIN & SIMPLE . . . there's no good reason for less accurate speedometers and there are numerous good & safe reasons for a more accurate speedometer.

ALSO . . . while I'm at it, if anyone want's to talk about something that's unsafe, let's talk about turn-signals with no sound indicators that can get you in a world of hurt when others act, subject to your telegraphed intentions.
 
#21 ·
SURV69 said:
ALSO . . . it's not smart to get cyclist to go 50 to achieve an actual speed of 55,
Did you mean 55 on the speedometer to go 50 in the real world? The speedometers are "optimistic" (i.e. if they are incorrect, they say you are going faster than you really are). I think this is what you meant, I just wanted to clarify.

SURV69 said:
ALSO . . . while I'm at it, if anyone want's to talk about something that's unsafe, let's talk about turn-signals with no sound indicators that can get you in a world of hurt when others act, subject to your telegraphed intentions.
If you haven't already, you can find discussions about how to remedy this. It's a pain to do it yourself, but it doesn't seem to be a difficult project (although I haven't done it myself).
 
#22 ·
I meant 60.

The reason I mentioned the turn-signals was aggravation on my part about safety.

You're a safer rider when you know your speed and your a safer rider when you don't wander for miles with a turn-signal on.

I'll bet we're talking "pennies", for either or both of these issues to be addressed in the assembly of a Majesty.
 
#23 ·
SURV69 said:
I'll bet we're talking "pennies", for either or both of these issues to be addressed in the assembly of a Majesty.
Pennies, or free.

I believe both are due more to accepted/expected practices than anything else.

I don't know of any bikes that come with audible turn signals, but I admit I have very little experience.

As for the speed, I really don't know what the deal is. I know my car is essentially dead on, or at least it and my GPS are within 0.1 mph of each other. I haven't tested the bike yet. Still trying to decide on the safest, cheapest way of doing it (since I don't want to permanently mount it).
 
#24 ·
What if you could take the speedo off, and pull the needle off, and replace it 5mph Faster than it was? I'm probably missing a simple detail that would not make this work...

I meant slower... but you would have to engage the speedo somehow, like with a drill or the wheel spinning while you do this...even IF you could get the needle off....hmm
 
#25 ·
JonInKY said:
What if you could take the speedo off, and pull the needle off, and replace it 5mph Faster than it was? I'm probably missing a simple detail that would not make this work...
The problem is it's not linear. It's accurate up to about 30 and then goes off from there at different levels at different speeds.
 
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