When checking the odometer against the interstate mile markers over a hundred mile stretch, my '02 was within a few tenths of a mile; the '09 was + 2.5, and the '14 is + 4.2. I had hoped that with the new gauges on the '14 that the accuracy would improve but apparently that was not one of HD's goals. I guess they are trying to improve gas mileage. LOL

 

They improved gas mileage by making the odometer /speed reed 6 mph faster. figure mileage at the pump with a fast odometer WOW !

 

Harley done this so people would bring their bikes in for service more often

 

speedos run faster? my speedo seems to be 5 mph slower than my gps

 

My speedo runs 5 mph faster than my gps. Was wondering why I was getting passed so much and running 5 mph over. It's because I was running the speed limit.

 

I recalibrated my speedo with my Powervision so it was dead on with my GPS. At the same time, I put on a new header, A/C and did a few autotunes. My MPG went down...and now I know why. 40 "real" MPG isn't so bad after all.

 

While there is only one speed sensor, there are two meters. Each meter may indeed be using different calculations off the sensor in the ecu? I don't know enough about it to know? But I don't think the motor company is running a scam, more likely just running high tolerances (poor quality control).

 

Misinformation and rumor are common for this subject. There is no U.S. law regarding private vehicles' speedometer accuracy. It is the threat of lawsuits which keeps them from reading low, as well as compliance with European requirements.

Under U.S. law speedometer accuracy requirements apply only to commercial buses, trucks, and truck-tractors. That law (actually a rule) is:

§ 393.82Speedometer.
Each bus, truck, and truck-tractor must be equipped with a speedometer indicating vehicle speed in miles per hour and/or kilometers per hour. The speedometer must be accurate to within plus or minus 8 km/hr (5 mph) at a speed of 80 km/hr (50 mph).
[70 FR 48054, Aug. 15, 2005]

Europe, on the other hand, states that speedometers cannot read low but give a large range that they can read high:

European Union Directive 2000/7/EC set the requirements for speedometer accuracy.

There are two main requirements when tested:
1. That indicated speed is never below actual speed.
2. That indicated speed is never above 110%+4 km/h of actual speed.

For actual production motorcycles and motor tricycles, the upper limit increases to 110%+8 km/h (but remains 110%+4 km/h for mopeds).

So for a production motorcycle rolling at an actual 80 MPH, the indicated speed can't be below 80 MPH, and can't be above 92.97 MPH.

Link: EUR-Lex - 32000L0007 - EN

Since many vehicles are sold on both continents, and there is no U.S. law for private vehicles' speedometer accuracy, they tend to adhere to the European law.

Note that the speedometer and odometer may not necessarily agree with each other. For example, the 2009 Ducati Monster 1100 I once owned stated right in the owner's manual that the displayed speed is increased by 8% of the measured speed, so while the odometer was accurate, the speedometer read 8% high.

 

This is correct. Making changes to the speedometer calibration has no effect on the odometer. I tried various settings (real high and low) using my PV for the speed calibration and it has zero effect on the odometer readout.

 

Not jumping into this argument, but when 6 of us go on a 4000 mile trip everyone has a different odometer readings and everyone seems to say theirs is the most accurate one. I use a GPS and its different than all of us and I call that the bible. My speed is off 2-6 mph depending on speed, but I dropped to a 30th frt gear.