I got the recalibrating procedure off of this forum and had it on my pc:
1. Make sure the speedometer is in MPH. There will be a dot in the upper right hand corner of the first digit in the odometer if it is in KPH. If it is in MPH it will not have a dot.
2. You will need two miles of non-stop road. The closer you are to 2 miles the better the calibration. Stop at the beginning of the two miles and turn the bike off. Hold down the speedo button and turn on the ignition switch (keep the button held in). You will see "-_-_-" in the display. Release the button when you see that and wait a couple seconds then press it again, the display will show "0------0". Ride two miles and stop immediately.
3. Press the speedometer button again, the display will show a number. For a 2003 chopper with out any pully/tire size changes you should see appox 101,000 in the display. Press the button one more time, pressing it the second time stores that number as the calibration.
You can repeat the process at anytime if you have a problem. I would keep the bike under 60 during the calibration process. If you are about 500 pulses plus or minus I wouldn't worry too much, you shouldn't notice the difference.
If you find you are in KPH mode instead of MPH simply turn the key off, press the speedometer button and hold it in while you turn the key on. You will see "-_-_-" in the display. Keep the button held in for ~7seconds more and you will change modes. A common calibration issue on some of the older speedometers was that it was accidentally placed in KPH mode, we got rid of this on the newer versions.
The speedometer is counting the pulses as you drive 2 miles, the more you go over two miles the more the speedometer will count.