Hey guys, I have noticed that my speedo has been off a little at higher speeds. After running the GPS on my bike last weekend it seems to be off 5MPH at speeds greater than 60. It is reading 5MPH fast... if my speedo say 70, GPS says 65... and the GPS is dead on with all my other vehicles. It really isn't a huge problem but I like everything to be working as it should so if it is a fairly simple fix I would like to fix it. Also running a PCV if that makes a difference. Thanks in advance!

 

From what Ive read you cant do it with the PC V . if you had a "Flash Tuning" Device it is my understanding that it would be an easy adjustment. Power Vision, TTS, SERT etc can calibrate the speedo

 

You are probably also in the market for a new back tire. Am I right?

Those speedos are usually right on when new but, as your tire wears down it has to spin more times to cover the same distance. Most people would never notice this, but having a GPS for speed comparison makes it easier to spot.

Mine has been off by 3-3.5 mph and corrected itself after tire replacement every time.

 

My understanding is that they *intentionally* show 5-8% higher than actual speed.

 

My rear tire has 800 miles on it... changed it over the winter/spring build and just completed that 2 weeks ago.

 

This topic has come up several times before and from what I've seen here on the forum and also seen on the two H-D's I've had the speedo's seem to read 3mph FASTER than the true speed that a GPS will give you. I'd say 70-80% of the guys here seem to report 3mph difference. Your's at 5mph is a bit more than average obviously.

As to your question, I can't answer that but am interested in the answer as I also like things to work as they should. But I guess if I had a preference I'm glad the true speed is a bit LOWER than indicated rather than higher (could get you a ticket if you're pushing your luck).

 

All the electronic speedometers on the newer bikes (metric and harleys) are off incalibration. The signal being sent from the speed sensor to the ECU and then directed to the speedometer requires a product that allow you to change the frequency in-order to correct the speed being displayed Here is such a unit made to correct a Honda http://www.cyclegear.com/eng/product...tor/web1006886

Hope This Helps!

Bill

 

Mine is off by about 3 to 3.5 versus the GPS. I assume this means the odometer is affected as well. If so, at 5 mph (if it was consistent at all speeds) would put your odometer off by 50 miles (more) per thousand.

 

Or maybe not since based on above might not affect odometer.

 

The harley spec for speedos is +3 to +5%. If you use an after market correction device ,
Ex: Dakota digital... Your 6 speed indicator light and cruise won't work. The speedo and odometer will be right though. The best way is through the ECM with a tuner such as TTS. There might be others out there as well. I have a TTS tuner and was able to dial it right in. Good luck .