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[Ed Ramberger - One_Screamin_Eagle]

Can the Screaming Eagle Pro Race Tuner modify the ECM to reflect a change in gearing from a 32T to a 31T transmission sprocket?

Changing the gearing in the primary will not affect the speedo.  Changing the gearing at the front or rear belt pulley will change the speedometer and the Super Tuner does not change speedo values.  You will need to use an aftermarket item that changes the signal from the speed sensor, or a tuning device that changes speedo values.

[Smitty2u]

Well....  I did check my speedo last fall against my GPS and it was nuts on.  So if I do nothing my speedo will be reading 1.5 miles fast at 50 MPH.  For every 1000 miles traveled another 31 miles above miles traveled will be added to the odometer.  I will have a talk with my builder and see how familiar he is with the TTS Mastertune and go from there.  I do appreciate everyone feedback.  Always nice to get some feedback.

Smitty

[glens]

You might wait just a bit before getting a TTS, assuming you even wind up doing that.  They'll have some new and shiny sort of system out any day now, so you'd either want that one or maybe pick up one of the "old" versions a bit cheaper.

[dlaws01]

 In Germany speedos have to read slightly high by law, this does not apply to GPS units so I trust Garmin more anyway. .96 would not even be enough to compensate my speedo's high reading.


Here in the states, most speedos will indicate on the low side. I don't know what the regulations require as far as accuracy. Personally, it wouldn't be enough change for me to worry about doing a recalibration of the speedo. JMHO

[glens]

Our friend wikipedia says about speedometers:

"Vehicle manufacturers usually calibrate speedometers to read high by an amount equal to the average error, to ensure that their speedometers never indicate a lower speed than the actual speed of the vehicle, to ensure they are not liable for drivers violating speed limits."

and under the subsection on the United States:

"Federal standards in the United States allow a maximum 5 mph error at a speed of 50 mph on speedometer readings for commercial vehicles."

I have never had a vehicle indicate low unless I'd put taller tires on or something of that nature.  Typically they have been a couple or three percent high.

[Steve Cole]

One thing you all need to remember is that as the tire wears the speedo will be wrong. I haven't check it in a long time but if memory serves me right over the life of the tire the speed will change about 4mph. So where do you adjust it for becomes the question. I myself like to set it for a 1/2 wore out tire, that way the error over the life of the tire is as small as possible but for some time you will be either side of the real number.

[grc]

The tolerance for speedometer's at my former employer was -1/+5 at 60 mph indicated.  As noted by glens, the tolerance is biased toward the high side to make sure we weren't blamed for speeding tickets.  In actual practice, our speedometer supplier was able to maintain actuals of -0/+2 over time as evidenced by their statistical process control charts that I had opportunity to review occasionally.

Mr. Cole stole my thunder on another point I was in the process of posting before I noticed his post.  If the actual error turns out to be 1.8 mph at an indicated 60 mph (3%), that is actually better than most Harley riders report on their stock bikes.  I don't know that I'd go out and spend $500 to correct that tiny error, and then have the error creep right back anyway as I wore out tires and then replaced them with new.  You will never achieve perfection, since you are always dealing with a moving target.  Spend the $500 on something important, like a better front suspension.


Jerry

[Smitty2u]

The tolerance for speedometer's at my former employer was -1/+5 at 60 mph indicated.  As noted by glens, the tolerance is biased toward the high side to make sure we weren't blamed for speeding tickets.  In actual practice, our speedometer supplier was able to maintain actuals of -0/+2 over time as evidenced by their statistical process control charts that I had opportunity to review occasionally.

Mr. Cole stole my thunder on another point I was in the process of posting before I noticed his post.  If the actual error turns out to be 1.8 mph at an indicated 60 mph (3%), that is actually better than most Harley riders report on their stock bikes.  I don't know that I'd go out and spend $500 to correct that tiny error, and then have the error creep right back anyway as I wore out tires and then replaced them with new.  You will never achieve perfection, since you are always dealing with a moving target.  Spend the $500 on something important, like a better front suspension.


Jerry

Good point.  I will probably hang on to my cash.... Can always look for a solution at a later date if it's something I need to address.