Topic: Motogadget Speed Sensor Reed Switch Failure

[ladyrocket]

I wired up my CB750 about 4 years ago with an M Unit Blue and a Motoscope mini.  I put the speed sensor reed switch under the shift cover sensing the magnet on one of the front sprocket bolts.  This was very accurate and worked great up until about 75mph and then the motoscope gauge would start reading all over the place.  I tried messing with the reed sensor distance to the magnet to get it essentially 1mm away, but it never seemed to make much of a difference.  I wonder if it's because I split the one signal from the speed sensor between the M Unit and the Motoscope as Revival has an article saying this can cause issues, but I just kinda ignored it and avoided the problem by not riding that fast haha.  However, at the end of last year my auto off turn signals stopped working.  Couldn't think of a reason why...  Then when I got the bike out this spring, the speedometer wasn't working.  I checked the continuity of the reed sensor w/ and w/o a magnet and there is no continuity.  So I've ordered a new one (since I can't find my spare!).

Has anyone else had issues with the speed sensor at high speeds (over 75mph)?  Ideally I'd like my speedometer to work at all speeds, not just slower than 75 haha.

Has anyone else had a reed sensor fail on them?

Thanks

[calj737]

I wonder if it's because I split the one signal from the speed sensor between the M Unit and the Motoscope as Revival has an article saying this can cause issues, but I just kinda ignored it and avoided the problem by not riding that fast haha.

Huh?

Has anyone else had a reed sensor fail on them?

No.

[ladyrocket]

Cal, any thoughts on why my speedometer stopped reading accurately above a certain speed?

This is the article I was referring to: https://revivalcycles.com/blogs/technical-articles/speed-sensor-mo-unit-blue-and-gauge

I have mine wired up exactly like that, with the one speed sensor split to both AUX2 on the M Unit blue and up to the motoscope mini.

[calj737]

First, I’m not sure why you running the sensor to the mUnit. I would simply run it straight to the Mini for speed reference.

That article provides adequate clarification that splitting can induce an error. I would hypothesize that previously running below 75mph allowed sufficient reference to send a strong enough signal for both legs. But, exceeding that could be the threshold of its signal strength.

I’d wire straight, then go back and calibrate the wheel diameter for accurate readings.

[ladyrocket]

First, I’m not sure why you running the sensor to the mUnit. I would simply run it straight to the Mini for speed reference.

That article provides adequate clarification that splitting can induce an error. I would hypothesize that previously running below 75mph allowed sufficient reference to send a strong enough signal for both legs. But, exceeding that could be the threshold of its signal strength.

I’d wire straight, then go back and calibrate the wheel diameter for accurate readings.

Makes sense.  I'll do that.  I think the M Unit blue only uses the speed sensor for the auto off blinkers.

Thanks!