S
sledhedXP
Member
So I was running an ECU from a 2016 belt drive Axys RMK in my 2017 chain drive Axys RMK today (long story as to why but it doesn't matter to my question). I knew the speedometer would be off since the drive ratios are different. I was thinking maybe 20%.
But yesterday I hit 118mph on a short straight stretch of trail according to the PIDD gauge... I don't think I was even doing 50 actual ground speed... I expected to be off maybe 15-20% (I could calculate the actual % I would expect based on different gear ratios and the diameter of the 3" drivers but again doesn't matter right now).
Is there something completely different about the pickup for the speedometer sensor? I thought they both worked off of the hall effect on the disk brake rotor... maybe a different number of holes in the rotor or something? Sensor is on the brake rotor...
On second thought:
What I am really looking for is someone who has some detailed knowledge of how the speedometer pickup works on the belt drive and chaincase, if there is some kind of "converter" in the wiring or in the ECU, I know the ECU records hours and the gauge records miles (I am sure I piled up a few miles on that ride), but does the ECU tell the gauge the speed, based on some internal calculation of some sort? It would seem so, since the only thing I switched was the ECU. ECU #1 from 2017 chain drive: accurate speedometer, ECU #2 from 2016 belt drive sled" wildly optimistic. And yes, I made sure the injector color and oil pump number was set correctly for my sled.
But yesterday I hit 118mph on a short straight stretch of trail according to the PIDD gauge... I don't think I was even doing 50 actual ground speed... I expected to be off maybe 15-20% (I could calculate the actual % I would expect based on different gear ratios and the diameter of the 3" drivers but again doesn't matter right now).
Is there something completely different about the pickup for the speedometer sensor? I thought they both worked off of the hall effect on the disk brake rotor... maybe a different number of holes in the rotor or something? Sensor is on the brake rotor...
On second thought:
What I am really looking for is someone who has some detailed knowledge of how the speedometer pickup works on the belt drive and chaincase, if there is some kind of "converter" in the wiring or in the ECU, I know the ECU records hours and the gauge records miles (I am sure I piled up a few miles on that ride), but does the ECU tell the gauge the speed, based on some internal calculation of some sort? It would seem so, since the only thing I switched was the ECU. ECU #1 from 2017 chain drive: accurate speedometer, ECU #2 from 2016 belt drive sled" wildly optimistic. And yes, I made sure the injector color and oil pump number was set correctly for my sled.
