Speedometer Accuracy
Road Captain
Joined: Oct 2007
Posts: 673
Likes: 4
From: Charlotte NC
Speedo out of calibration
The spec for the speedometer is +3 to +5%. Harley allows this much variation.
Aftermarket calibrators work but with some issues on newer bikes. When the bike is completely calibrated the 6th gear light and cruise will not work. I went down this path a while ago and tried several calibrators with the same results. I got my SERT updated to a TTS unit with the calibration through the ECM and problem solved.
Aftermarket calibrators work but with some issues on newer bikes. When the bike is completely calibrated the 6th gear light and cruise will not work. I went down this path a while ago and tried several calibrators with the same results. I got my SERT updated to a TTS unit with the calibration through the ECM and problem solved.
Seasoned HDF Member
Joined: Jul 2007
Posts: 6,336
Likes: 67
From: SW Minnesota
Check it yourself with a stop watch and this chart. Set your bike on cruise, on a flat road, at an indicated 60 mph, and go past several mile markers.
chart courtesy of Mn State Patrol. We gave these out to our MSF students in Mn. Jap bikes, and BMW's, seem to be very optimistic on speed. Harleys run 2-3 + over actual speed.
chart courtesy of Mn State Patrol. We gave these out to our MSF students in Mn. Jap bikes, and BMW's, seem to be very optimistic on speed. Harleys run 2-3 + over actual speed.
Banned
Joined: Feb 2009
Posts: 6,259
Likes: 5
From: NW NC
I have my 01 FLHR and several vehicles. No matter what I have a 1 mph variance between the GPS and whatever it is being used in or on. Close enough for me. About the same with the highway traffic/speed readers.
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Ultimate HDF Member
Joined: Feb 2006
Posts: 5,939
Likes: 3
From: TX
The variance is common.
Heck if it's perfect with a new rear tire, it's gonna loose accuracy as the wears. Same is true of your cars.
If ya have one way off, you can fix it with a TTS tuner. It provides access to VSS frequency in the ECM, in addition to allowing for proper tune.
Heck if it's perfect with a new rear tire, it's gonna loose accuracy as the wears. Same is true of your cars.
If ya have one way off, you can fix it with a TTS tuner. It provides access to VSS frequency in the ECM, in addition to allowing for proper tune.
