Speedo sensor accuracy

[halfsquid]

I was riding along, not too fast :p and noticed my speedometer was reading a hair past 135 mph.

Has this ever happened to anyone else?

[ersigh]

Hmmm, my speedo has said that ...

course now I KNOW my speedo is bad, cuz' I got a ticket for doing 90+ but my speedo said 85.

[halfsquid]

85 mph indicated and they said you were doing 90+?

I know speedometers are not that accurate but that is a big difference.

On my bike it seems I am going slower then what the speedometer reads

Does anyone know how accurate they are? If so how did you test it? I know this could be different from bike to bike but I am curious about other bikes.

Thanks.

[rb643]

I sometimes wonder how accurate my speedo is too. If you're really worried about it, there is a device called the Yellow Box that can recalibrate speedos. It should work on the SV, but you should contact Black Robotics just to make sure. Here's the link.

http://www.blackrobotics.com/

[ersigh]

Mine is off because of changes I made to the bike.

I went from a 120/60 to a 120/70 front tire, and I went smaller on my front sprocket.

[linp]

Just carry a GPS if you're wondering about your speed.

[bwarbiany]

Okay folks, as I mentioned, I did my springs & emulators... Which means, of course, that I had to remove my front wheel... This morning on the way to work, my speedo sensor stopped working. While this might be a good way to keep miles off the clock, I don't know that I like this. At a stop light, I turned off the switch, and now it seems to work again. Has anyone had this happen? Should I expect it to happen again? Any thoughts on how to fix it?

Brad

[Gmoney]

hey brad,
when you put the bikes front wheel on you might have not put the sensor back correctly. their is a tab of the forks and a tab on the speed sensor, that need to be resting together. i almost messed it up when i put my wheel back on. or maybe the cable that goes in the sensor got damaged.

thants my 2 cents.. hows those emulators? they must make a big difference.

James

[bwarbiany]

The emulators rock...

I got the tab lined up, and hopefully the cable is fine... It might just have taken a few miles to seat the sensor properly... I'll have to see if it happens again...

Still happening intermittently... I don't know what the hell is going on... Any ideas?

Brad

[linp]

Maybe it's time to install that Sigma bicycle computer?

[Denys]

Can someone tell me why some believe that changing your spocket size has any effect on the speedo's accuracy. It just does not make any sense when the sensor is on the front wheel.

Now, I know in Leigh's case she's changed her tire sizes therefore disrupting the sensors calibration.

Denys

[bwarbiany]

Hey, for those of you who saw it this weekend, my speedo sensor is toast... Totally destroyed internally, so I need a new one... Anyone know where to get it? I was trying to get in touch with Saddleback, but they're closed Mondays :(

Also, I think my chain and sprockets are just about shot... I think I could probably replace these with assistance & tools... Has anyone down here already done this (Gregg?) that can give a hand, or that has the tools? I might just end up biting the bullet and going to the dealer, but I really prefer not to...

Brad

[Stinky]

You could try this:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=1864857335

[Burst]

Brad,

If you want to do the chain yourself, you will need to get a new chain that has a clip type master link. DO NOT GET ONE THAT HAS TO BE PRESSED..... Get the sprockets and chain and head down to my place. I recommend a 46 tooth rear sprocket. I didn't lose very much top end at all and it gets there much much quicker than it used to. The lower gearing was GREAT up at Palomar on Sunday. Much better drive out of the corners...

Let me know if/when you want to come down to do the swap. I still need to change the front sprocket since I was too lazy to do it. Only swapped out the rear.

[Burst]

For the speedo sensor you might check the SVRider for sale list. I know I have seen a few listed on there that only have one of the drive teeth broken off. Still completely functional with three of the four teeth tho. Much cheaper way to go than new from the dealer.

[bwarbiany]

Okay, I found out that I only need the magnet for the speedo... I guess that's only $25...

Especially since that one on ebay has broken teeth, I don't really want to buy that :)

Well, the speedo sensor is in stock at OC Suzuki now (they were actually really good to me when I went in, and the part arrived fairly quickly... overall not bad)...

And I'll be using a 15 tooth AFAM steel front sprocket, DID X-Ring Gold 525 chain, and Sprocket Specialists 46 tooth aluminum rear sprocket... Hopefully it'll hold up for a while...

Now, just gotta go to Gregg's sunday morning to put it on, ride down to Palomar, and see how it all works :D :D :D

Brad
(can you say *wheelie monster*)

[Punkbrad]

today, while doing about 70 on the freewway, my spedo started jumping from like 70 to 30 and jumping all around, and then just stopped, a long with the trip meter. then, as i slowed for traffic and eventually stopped, it started workign fine again?

anyone experience this?

brad.

[Burst]

sounds like you need a new speedo sensor. I just happen to have one in perfect(but dirty) condition sitting in my garage.

[Punkbrad]

Originally posted by Burst
sounds like you need a new speedo sensor. I just happen to have one in perfect(but dirty) condition sitting in my garage.

I'll take it!

now what?
:D

[Burst]

pull off your front wheel first to make sure that you do in fact need a new sensor. Pull the little magnet dealy out of the sensor. it should have four "teeth" on it. chances are there are no teeth and lots of little chunks of plastic lookin stuff in there. If the teeth are there then you have an electrical problem which I cannot help you with. :D

[Punkbrad]

thats gregggg... i will try that, it is working fine now, so it may be *shudder* electrical. but i wont fuss with it until it does it again.. it was fine after that. funny, cuz it started BEFORE i rode 50 miles in the rain this morning, but whilst in the rain, it started working fine again, hehe.. maybe the rain washed the problem away!

[bwarbiany]

Originally posted by Punkbrad
thats gregggg... i will try that, it is working fine now, so it may be *shudder* electrical. but i wont fuss with it until it does it again.. it was fine after that. funny, cuz it started BEFORE i rode 50 miles in the rain this morning, but whilst in the rain, it started working fine again, hehe.. maybe the rain washed the problem away!

Sounds like what happened to me, actually... For me it was kinda on the fritz for a while, and then just died for good...

I'd suggest pulling the wheel, and replacing the sensor... If you take the front wheel off, and aren't REALLY careful when you put it back on, you'll bend those teeth, and it's all downhill after that...

But the magnet is only a $25 part, so it could be worse...

[Punkbrad]

well, i pulled the wheel, and indeed the magnet inside was reduced to a little pile of magnetic dust, and it was all jizzammed and grounded all up in that beeyatch.

anyone have a sensor magnet they dont want??

brad.

[Tillers_Rule]

Originally posted by Denys
Can someone tell me why some believe that changing your spocket size has any effect on the speedo's accuracy. It just does not make any sense when the sensor is on the front wheel.



In the case where the speedo sensor is on the front wheel, sprocket size has absolutley NOTHING to do with the speedometer.

Bikes that DONT have the speedo sensor coming off the rear wheel, will be affected by BOTH gearing and tire changes, as the computer takes it all into account when calculating the speed.

*note from Moderator; the last sentence doesn't make sense and I am not sure how to correct it.

[Burst]

PB,

you been doin a lot of wheelies? that and not taking care when putting the wheel back on will destroy the magnet. The wheelies will only doin damage if you have the front wheel up long enough for it to stop spinning. Then when you set it back down the wheel suddenly starts spinning and takes a little chunk out of the magnet each time, until you are left with a "pile of magnetic dust"...

check with ronayers.com for the magnet. as bwarb said, should only be $25 or so. if the part is not listed on their site, give them a call. they usually have the best prices on any OEM part I have looked for.

[crazyspin]

I think it may be because the speedometer sensor on the left side of the wheel is slipping, or any wire connexion is bad, maybe inside the headlamp.
Good luck!!!!!!

[Punkbrad]

Originally posted by Burst
PB,

you been doin a lot of wheelies? that and not taking care when putting the wheel back on will destroy the magnet. The wheelies will only doin damage if you have the front wheel up long enough for it to stop spinning.

who mee?? umm, i think that is it, im keeping the wheel up till the wheel stops, and until recently, some of my set-downs were a bit hard...

anywhoo.. im getting a new magnet, so its all good now !

thanks gregg, until then, im racking up no miles on the ol SV! haha

Thanks for your help!

Brad.

[Punkbrad]

well kids, went to the Victrorville Dealer, and the part is only 18 bux plus tax...!!

not too bad, i ordered one up, and oh yeah, i think im gonna buy a Kawasaki Vulcan Drifeter... haha..

im serious, they have a brand new one in there for a screamin price.....

i think that its just my speed, and style, without having to break the bank... 6K and its mine. its black though, not maroon like this one...

[FLSVRider]

I think those fenders and seat look gay.

[smolvar]

What is it about the stock speedo sensor that makes it incorrect at higher speeds?

It seems the same type of magnetic device is used on the Sigma bicycle computer, yet people praise its accuracy.

[bwarbiany]

Originally posted by smolvar
What is it about the stock speedo sensor that makes it incorrect at higher speeds?

It seems the same type of magnetic device is used on the Sigma bicycle computer, yet people praise its accuracy.

I don't actually know, but I'll give it a shot...

It has to do with how far it is from the axle. Basically, because of the way it is dest up, you have 4 big tabs compared to a small circumference circle of travel. Due to this, you get a lot of effects where even though a tab may not be actually passing over the sensor, it's close enough to throw off the measurement. And with any speedo, the inaccuracy will be higher at higher speeds.

Compare that to the Sigma computer, which is a lot farther away, and a much smaller magnet. Since it's so much smaller, it only spends a very small percentage of time at/near the sensor. This makes it a lot easier to account for the error.

Think about it this way. If you had ten data points where a sensor was "triggered". And that sensor triggers for 80% of the total time that you're sampling. This makes it fairly hard to figure out exactly the change when you determine the time between the center of the sample time. But if you trigger for only 1% of the time, you know even if you miss the actual center by a little bit, you're only off by a small amount, so you'll be more accurate...

I'll bet that made no sense, but that's my thoughts on it... I think I need a protractor to explain it better :geek:

[stickyc]

I hooked up a cycle computer and found that when the bike's speedo read 90, my speed was actually 85ish. I figure the 'puter is more accurate since I actually did a measure of the circumfrence of the tire with a tape measure. This is on an '02 SV with the stock front tire.

I just figured it was a good thing since it'd keep me that much lower under the limit :)

[smolvar]

Originally posted by bwarbiany

Compare that to the Sigma computer, which is a lot farther away, and a much smaller magnet. Since it's so much smaller, it only spends a very small percentage of time at/near the sensor. This makes it a lot easier to account for the error.


I guess this begs the question, why didn't Suzuki just make a single small magnet and sensor (like the Sigma) versus the ring. I have to imagine the costs are the same.

[ElPatron]

Can anyone give a figure on the speedo error on an '03? 80 doesn't feel like 80, and about the only time I break that is at night, so everything is a rush of wind and Texas cagers(everything's bigger in TX, including the assholes....):finger:

[McTwig]

how in accurate is the speedo? if the speedo says 125mph, how fast am i accually going? how much would it cost to fix this problem?

[linp]

On the first page of this thread.
Originally posted by rb643
I sometimes wonder how accurate my speedo is too. If you're really worried about it, there is a device called the Yellow Box that can recalibrate speedos. It should work on the SV, but you should contact Black Robotics just to make sure. Here's the link.

http://www.blackrobotics.com/

Prices
1 Yellow Box = $100 USD + $10 airmail, total $110 USD
2 Yellow Boxes = 2x $96 USD (ea) + $10 airmail, total $202 USD
3 Yellow Boxes = 3x $92 USD (ea) + $15 airmail, total $291 USD

[tmonroe]

Another thing to consider with Speedo accuracy is all of the things that can affect the diameter of the tire.

For example: When you buy a tire new, it has deep tread. As you ride, this tread gets worn off... which reduces the diameter of the tire. Since the speed is a calculation which includes the diameter of the tire, the speed displayed will change.

A heavier load on the tire will deflect the tire more also changing the diameter (a lighter load will deflect the tire less).

Increasing the air pressure increases tire diameter. Or decreasing it does the opposite.

Different tires will have different profiles.

I could go on, but basically, anything that affects the diameter of the tire will introduce some inaccuracy in the speedo. No speedo will be 100% accurate - except maybe by chance (a broken clock is right twice a day)\. Manufacturers build in innaccuracy because they can't legally sell a bike that reads less than what the bike is actually travelling (IE, they might get sued if a rider could prove that his brand new bike measured a low value and the rider got a ticket, or got in an accident)... Pretty much all bikes average somewhere around 5% low reading of speed...

[petec999]

Is there a way to re-calibrate the stock speedo? I am planning to put my new Diablo on (when it gets here). It's a 170, the stock a 160. I know about dropping the front end to compensate, but is there something that can be done to the speedo. With the new tire, I will be going faster than the speedo reads, which is not a good thing!

[Mathis650]

I know the variance depens on the bike. I actually have a friend that is a HP office here in GA and we performed a test a few weeks ago. I was travelling at an indicated 50ish and he said his laser showed me at 47. When I increased to around 60, it dropped to 56. Kind of cool to know what the police will see.


Scott

[clee454]

Well I got my silver 03 sv650s on Thursday and due to work and weather I didn't get to take it out untill today.
Today was great. I live in Sonoma County (nor-cal) a friend and I went on a 180 mile ride today very little traffic on the backroads at a pace that would make you cry. Damn this horrid break in procedure! Nothing like being stuck with a 65 mph limit on some of the best roads in the state.
So my question here is since I can do 65mph at 5000rpm in 6th gear what speed does 7500rpm in 6th gear correspond to.
Thanks,

[GMAN]

You will need to know the 6th gear ratio in addition to a couple of other things.

Use this calculator (http://www.cosportbikeclub.org/misc/SpeedCalc.html) to figure it out.

Oh, congrats on the purchase. :)

[clee454]

Hey GMAN thanks for the link I tried it and it seems to be a little generous. It says my speed at 5k rpm should be 70mph amd the speedo said it was doing 65mph. In my expirence speedos seem to error on the safe side ie. it says your doing 65 and your speed is really 63-64 on a calibrated gun.
Anyways it says at 7500rpm it should be doing 105mph which even with the error will make finishing the break in on my favorite twisties A LOT more fun than what I am stuck with for the next couple rides.

[pinhead875]

I went by one of those radars that show your speed under the posted speed limit sign. I was going 74-75mph indicatged on my bike, and the radar said i was going 68-69...

[SVelocity]

Originally posted by linp
On the first page of this thread.


Prices
1 Yellow Box = $100 USD + $10 airmail, total $110 USD
2 Yellow Boxes = 2x $96 USD (ea) + $10 airmail, total $202 USD
3 Yellow Boxes = 3x $92 USD (ea) + $15 airmail, total $291 USD

Has anyone installed this so called "yellow box"?

Chris