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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: alexis291 on July 10, 2017, 12:18:33 PM

Title: K1100RS speedo cal check
Post by: alexis291 on July 10, 2017, 12:18:33 PM

Hello All,


having read a number of articles on this topic, my suspicion that my speedo calibration is wrong has increased. So I am trying to check it by inputting a frequency generated by my laptop in place of the speedo sensor on the rear hub.


I found a useful site to do this (http://www.szynalski.com/tone-generator/) and made up a lead like the one shown here - http://www.k100-forum.com/t2038-karamba-speedometer-calibration-program-tutorial.

Sure enough my speedo (and odometer) start working when a frequency is introduced from the laptop into the wiring harness (80mph at 50Hz in my case).


So I have now measured the rolling circumference of my rear wheel (1.986m), and with the sensor ring having 6 teeth, this gives me 0.740mph / Hertz - which appears to be about half of what I was expecting.


My question is whether anyone knows if the speedo sensor is triggered from both edges of the teeth on the ring, in which case my calibration would change to 1.480mph / Hertz and the 50 Hz I input would give a true 74mph, instead of the 80 my speedo showed (ie an 8% error, which appears to be normal!).


I don't have an oscilloscope so I can't check this myself, but has anyone else ?


Thanks

Title: Re: K1100RS speedo cal check
Post by: alexis291 on July 10, 2017, 12:19:26 PM

PS - feel free to point out any stupid mistakes in my maths !