Speedometer reads 10 mph high

I was out on my new to me 2011 WR250R and thought the speedo wasn't right so I hooked up a GHS and checked it.  Pretty consistently 7 to 10 mph high.  Are there any adjustments for this?  It has an aftermarket 47 sprocket....does that make a difference?   Thanks.

Yes and they all do that.  The speedo is not off the front wheel, but off the engine.  Any change in gearing will change the speedo caibrationl. They are not really accurate stock but with a 47 tooth, mine was about 20% off.  The only way to correct to to spend some bucks and get an electronic/programmable speedo corrector, such as 12 O'Clock Labs:

http://shop.12oclocklabs.com/index.php?route=product/product&product_id=59

No affiliation.  Just a satisfied customer as mine works great.

Thanks for that. I'm less concerned about the speed but more about the odometer. Just ordered one of these units, quick and easy.
Thanks again.
  

To get my WR right on the money with stock gearing I had to go -11% with a SpeedoHealer.

Your odometer is on the money, your speedo is high, if you correct the speedo, you will have to add the % of correction to your mileage, in my case I have to +11% to whatever the Odo displays.

Today I'll go out with the GPS and get a good reading for comparison.  I was thinking 55mph on the GPS as a base point.  Should I get it faster?  Does it matter?

Did a slow read on your post. Odo is currently correct without the speed correction? I think I would rather have the right odo. The speed doesn't matter that much on this bike but the total and trip odo does. Hmmm.   

Bob Hancock wrote:

Today I'll go out with the GPS and get a good reading for comparison.  I was thinking 55mph on the GPS as a base point.  Should I get it faster?  Does it matter?  

I found my speedo was consistently off at any speed, so No the Mph doesn't matter.

Bob Hancock wrote:

Did a slow read on your post.  Odo is currently correct without the speed correction?  I think I would rather have the right odo.  The speed doesn't matter that much on this bike but the total and trip odo does.  Hmmm.    

The Speedo matters to me because all of the One Horse Towns I ride through see anybody going as little as 2 Mph over as a a source of income or revenue enhancement  

Thanks for a good discussion. I'll do a careful comparo today between speed and distance. In my part of the woods I can live with mentally adjusting speed...LEO's generally leave you alone if you aren't being a nutter, but I prefer correct mileage both for riding and bike odo purposes.

Rode 105 miles (per the WR odometer); 94 miles per the GPS trip log. A nominal diff of 11%. Trip was about half dirt, half asphalt.

Compared indicated speeds and WR speedo showed fairly consistently 9 mph faster than GPS over a wide variety speeds. Per the 12oclockLabs calculator this is a Correction Percentage of -13.0%

So the WR thinks it is going 11% farther 13% faster with my aftermarket 13/47 sprockets.

If I program the -13.0 into my unit will the odo be better, worse, or same? Comments? (I'm an English major so be kind.    )

If the Odo is the reading you want the most accurate then -11% is what you would use to get the mileage the most accurate and did you roost any while in the dirt? Cause any kind of wheel spin will change your outcome.

Not much wheelspin at all. Settings were easy to do; will check again against the GPS when the wx clears up.