speedo accuracy

[NighthawkVTX]

Hey all,
I've had 2 VTXs in the past, both, had speedometers that were off by ~10%. I was curious if Honda followed suit with the Valkyrie ?

[Steel cowboy]

Yes, my speedo is always faster, never matches my GPS.

[Bone]

Yes, always travel 5 mph over the posted speed with my 98 Tourer and have never been stopped.
In the western states with a posted 75 mph at 80 cars were going around me like I wasn't moving.

[Hook#3287]

It's a known defect of the Valkyrie, the incorrect speedo.  It seems to be about 5 mph faster.

I wonder, has anyone ever tested the odometer?

I've done it with those measured miles markers on the highways, and they seem close, but anyone done any REAL tests?

[Jess from VA]

It is a known fact that all Japanese bikes (no matter where they are built) have a built-in 5% error rate on all factory speedos (reporting faster than actual) for at least 30 years or so.  I have read this was to avoid the possibility of major fines by the US Govt on imports failing to meet standards.

There is a Yellow Box that can be installed to correct this.

I have read that this 5% error rate does not extend to the odometer (inflating miles over the life of the bike), and I could see this on the IS with an electronic speedo.... but how it is done on the std/tourers on a direct cable hookup I don't know.

[Firefighter]

My IS odometer does not match my GPS but been so long since I have worried about it I can't remember how much.

[John Schmidt]

For those with the I/S type pickup on the wheel, for a bit over $100 you can get an item called a Speedo-Healer. You wire it into the output line of the pickup, the output of the Healer then goes to the speedometer. It has something like a +/- 9999% correction availability, I used one on Carman Allens' bike when I did some conversions on it. You make a run down the road, possibly with a GPS, note what the speedo is telling you and what the GPS is telling you. Then go to their website and enter those two factors, it tells you what to punch in for exact correction. Then go back out and see if the speedo and GPS match....or nearly so. I set Carman's about 3mph high on purpose, told him about it some time later. It's a money saver that way. 

It was a simple installation, I just laid the unit on the battery cover under the seat. It's smaller than a pack of cigarettes.

[Steve K (IA)]

My I/S reads 1 - 2 mph slower that my Zumo GPS tells me.  I have Dunlop E3's which is a bigger tire.  I think that is what brings the speeds closer.

[h13man]

Mine registers 2 mph fast thru out the all speed ranges.

[Jess from VA]

With a 5% error, the faster you go, the more mph in error.

Indicated         Actual         Error

35mph - 5% = 33.25mph  (1.75mph)

50mph - 5% =  47.5mph  (2.5mph)

70mph - 5%  = 66.5mph  (3.5mph)

115mph - 5% = 109.25   (5.75mph)  (here, the awards and prizes get exciting, and depressing)

Of course, I would not expect the speedos to be mathematically perfect.  But this is the math.

I don't need a converter box, I just need to pay attention.