Speedometer error

[Beau57]

New owner (2 weeks), I haven't checked with GPS yet but it appears I have a very substantial difference in indicated and actual mph. At 80 mph indicated I have the entire mass on the interstate passing me (everyone usually does about 75). I have the correct size fron tire. Anyone else have any data. I am replacing tire in a few days and will calibrate with GPS then.

[MP]

They are off 6% or so.  Normal.

MP

[Jess from VA]

We're all off (at least) 5% on purpose.  (all Japanese bikes)

Beyond that, I don't know.

Your GPS can be a better speedometer.

Or this, if you don't have cable/sender/speedo problems.   http://www.yellr.com/

[Hook#3287]

The speedo's run a little faster than the bikes, which still are pretty fast.

If you do a search, maybe in the tech files or shoptalk you'll find more info.

[MarkT]

All of our Hondas read high - in our garage, Valyrie, Gold Wing, Magna.  At 75, it's about 5mph.  It's no accident.  I could get more precise measurement of the error, but so can you if you use your GPS.  BTW, the Gold Wing gets it's speedo reading off the transmission, and going from the recommended 60 profile back tire to a 70 - that is, the Valkyrie tire - corrects the speedo error almost exactly.  I wouldn't be surprised of going up 10 digits on the profile of the front tire on the Valk, would correct the error.  But them of course your odo will be short by the same %.  Doesn't matter much to me, I'm used to it.  And I usually have the Zumo mounted, so I have the actual speed indicated if I want it.

[Beau57]

Glad to know it wasn't a trend that all on the highway were speeding and my Valk isn't a "wuss".

[flcjr]

Not to get off subject here I guess I never gave it any thought until now but wouldn't the speedo error give you incorrect mpg calculations??

[Rocketman]

The odo and speedo are only partially common systems.  There are enough points at which the odo is independent of the speedo, that they each have their own independent errors.  So, no, the odo isn't gospel, but the errors are not tied to each other.  Your mpg calculations are odo based, so the odo error is what's important there.

Mark

[Printer Mike]

I want to take mine apart and calibrate it a little closer. Bet there's a simple way to get that needle to be more accurate.

[fudgie]

My bike said 85 but ISP said 79.  Speedo is off front tire. Back tire will make no differance. Just ride and subtract 5 mph if it bothers you to much.

[John Schmidt]

The difference has actually saved me a couple bucks I'm sure when it comes to being followed by a trooper or hit with radar. As for the odometer, in all the reading I've done on the subject it appears the odo in most vehicles are fairly accurate as opposed to the speedo. In many cases the testers have shown the speedo to be off by as much as 7-8 mph, yet the odo was within a couple tenths (or less) of a mile as to accuracy. Their final analysis was "the odo is found to be quite accurate even though the speedo may be off by nearly 10%."  Don't know if I buy the whole thing, but just passing on what I've read in recent years.

That said....the speedo being off isn't really an issue. I just set my cruise control on the bike to about 75 indicated, knowing I'm right at 70+/-  a couple mph. When I revamped a friend's Valk a couple years ago(trophy winner at InZane last year), the speedo was electric so I went to an I/S pickup on the front wheel. The speedo and tach were off a VTX1800C as I recall. The voltage from the I/S pickup was the same as the VTX trigger, but I found the wave form to be enough different so as to prevent the speedo from working with the I/S pickup. To get it to work, I had to use something called a SpeedoHealer(see the link below), similar to the Yellow Box. I wired it into the system and set it to read about 3mph fast, he likes to twist the wrist at times so figured it might save him a dollar or two. One thing we found with that setup was the odo was right on, even though the speedo was purposely set to read three over. The SpeedoHealer is easy to use, just figure out what your speedo is reading(has to be an electric one like the I/S), compared to what it should be reading. Then go on their site below and punch in the numbers, it will tell you what the setting should be to convert the system to read correct. Unit costs about $110 and works perfect. And, it has little LED readouts so you can see what your current settings are if you feel a change is needed.

http://www.healtech-electronics.com/

[Redline +]

Not to get off subject here I guess I never gave it any thought until now but wouldn't the speedo error give you incorrect mpg calculations??

I've tested my odometer several times using the 5 mile tests along the freeway. Mine is within .1 in 5.

Redline