Electronic Speedo

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Jerry Doe

Jerry Doe

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Hello all,

I was wondering if anyone else has had this issue:

I have a Smiths green spot electronic speedo on my 750 for 5000 miles. While riding the speedo is ok or at zero mph. It bounces from actual speed to zero and back. Its gradually getting worse. I already removed the magnet sensor and checked it for cleanliness etc. All good there. I checked all wiring and everything is fine. My conclusion is that the speedo has gone bad. Has anyone else experienced this? If so, is there a fix?

Sounds like I am gonna have to buy a new one.

Cheers, Jerry
 
You have a Tri-Spark and a Podtronics.
Unplug your reg/rec and take a ride round the neighbourhood and see if your problem goes away.


If that doesn’t turn up anything suspicious, check your connections - it sounds like a momentary loss of power to the gauge or the sensor.
 
gtiller said:
You have a Tri-Spark and a Podtronics.
Unplug your reg/rec and take a ride round the neighbourhood and see if your problem goes away.


If that doesn’t turn up anything suspicious, check your connections - it sounds like a momentary loss of power to the gauge or the sensor.
Click to expand...

yes it does sound like a momentary loss of power. I checked all connections twice. I will have another look at the wiring and maybe run new wires from the sensor. I took the tri-spark out and put in a Pazon. So you think it might have something to do with the rectifier? I guess I could try that. I am wondering why.

Thanks for the advice
Jerry
 
Well, Stephen Kelly from Tri-Spark found the Podtronics reg/rec to by quite ‘chatty’ in terms of EMI or RFI and attributed it to the reason his Classic Twin electronic ignition units miss at between 3,000 and 4,000rpm.

Just wondering if that can affect your speedo in the same way, on the grounds there is a similar conversion of mechanical rotation to an electronic pulse involved.

I’m only guessing here, but it’s a really easy thing to test for by unplugging the reg/rec and going for a quick spin by battery power.
 
gtiller said:
Well, Stephen Kelly from Tri-Spark found the Podtronics reg/rec to by quite ‘chatty’ in terms of EMI or RFI and attributed it to the reason his Classic Twin electronic ignition units miss at between 3,000 and 4,000rpm.

Just wondering if that can affect your speedo in the same way, on the grounds there is a similar conversion of mechanical rotation to an electronic pulse involved.

I’m only guessing here, but it’s a really easy thing to test for by unplugging the reg/rec and going for a quick spin by battery power.
Click to expand...

I have lost a tacho due to interference from tri-spark. That was before they suggested putting a resistor in the line to the tacho. I am not sure about the speedo as it’s a separate circuit. I am going to get into it again and figure it out, will let you know...
 
Jerry Doe said:
I have lost a tacho due to interference from tri-spark. That was before they suggested putting a resistor in the line to the tacho. I am not sure about the speedo as it’s a separate circuit. I am going to get into it again and figure it out, will let you know...
Click to expand...
Jerry,
I have the electronic speedo on mine also that had the same problem. I would make sure that you have a good ground. Any blip on the circuit will make the speedometer erratic while riding. I re-did all my connections and problem solved. I also got in touch with Peter Wilkinson at the company that makes these instruments and he was very helpful.
technical@caiguage.com
I love the way they work!
 
Jerry Doe said:
Hello all,

I was wondering if anyone else has had this issue:

I have a Smiths green spot electronic speedo on my 750 for 5000 miles. While riding the speedo is ok or at zero mph. It bounces from actual speed to zero and back. Its gradually getting worse. I already removed the magnet sensor and checked it for cleanliness etc. All good there. I checked all wiring and everything is fine. My conclusion is that the speedo has gone bad. Has anyone else experienced this? If so, is there a fix?

Sounds like I am gonna have to buy a new one.

Cheers, Jerry
Click to expand...
Jerry,
I have the electric speedo on my bike and it works great other than it fogs up.Have you had this problem?
Thanks,Mike
 
YING said:
Jerry,
I have the electric speedo on my bike and it works great other than it fogs up.Have you had this problem?
Thanks,Mike
Click to expand...

My dad has a set on his '74 850, and they fog up from time to time as well. I have noticed it, but he has not complained about it. They do seem to clear on their own after a while.

It would bug me, but he doesn't seem too bothered. I think that he is just happy to have working instruments - LOL
 
Mine never fog up because I never ride in the wet. Find a turn off restaurant and have lunch or whatever. Fog up on originals are about nowhere for the moisture to get out. Maybe consider drilling hole(s) in a lower drier area to let moisture escape ?
 
Jerry I agree it's likely an intermittent poor connection. I love the new Smiths E-Instruments.
 
Torontonian said:
Mine never fog up because I never ride in the wet. Find a turn off restaurant and have lunch or whatever. Fog up on originals are about nowhere for the moisture to get out. Maybe consider drilling hole(s) in a lower drier area to let moisture escape ?
Click to expand...
I have been in touch with the company that makes them.Sent the unit back but still have the same problem.I am waiting for a replacement.I will ask them about drilling holes.The speedo works great other than the fogging.I can still read it but it is just frustrating as the tach is perfectly clear.The factory has been very good about getting back with me which I appreciate.Just want it perfect.
 
Could there be RF spikes affecting the speedo pick-up sensor/line from non resistor spark plugs/caps?
 
First for fogging instruments, I usually put a small desiccant bag inside the speedo to fix that. It works.

In my case this is what happened.

The rear hub Circlip behind the dummy axle popped out and everything moved. The brake plate was rubbing very slightly. Also the inside of the shoe holder. I did not notice . Due to the rubbing the Cush rubbers melted. The magnetic pickup looked ok and the wires had continuity.

I decided to go back to an analog speedo, drive and speedo with cable. I am ok with that. I also added Dons one piece rear axle. Fine piece of art, a new tire and new Cush drives. All is good.

Here is the most interesting thing. At around 85 I used to get a slight wobble on the front end. I have taken the front end apart 3 times, changed the springs and triple checked everything, but could never find the cause of it. Now since fixing the issue in the rear, the front end wobble is fixed. I can go way over 85 and it’s perfect. The bike is brilliant.

I think I’ll stay with the original speedo setup now. So I have an electronic speedo and drive for sale if anyone is interested. I am not sure if it works or not though, so don’t want much, I think the actual speedo might be ok.

I have an electronic speedo and tacho on my 850 and love it.

Jerry
 
I'm well pleased the Legendary Speedo & Tachograph I have fitted... that is until I go through Dartford tunnel that has average speed cameras fitted set at 50mph:( Just when I want to give it large to get the fantastic reverberation back off the tunnel walls:)
 
Jerry Doe said:
First for fogging instruments, I usually put a small desiccant bag inside the speedo to fix that. It works.

In my case this is what happened.

The rear hub Circlip behind the dummy axle popped out and everything moved. The brake plate was rubbing very slightly. Also the inside of the shoe holder. I did not notice . Due to the rubbing the Cush rubbers melted. The magnetic pickup looked ok and the wires had continuity.

I decided to go back to an analog speedo, drive and speedo with cable. I am ok with that. I also added Dons one piece rear axle. Fine piece of art, a new tire and new Cush drives. All is good.

Here is the most interesting thing. At around 85 I used to get a slight wobble on the front end. I have taken the front end apart 3 times, changed the springs and triple checked everything, but could never find the cause of it. Now since fixing the issue in the rear, the front end wobble is fixed. I can go way over 85 and it’s perfect. The bike is brilliantI think I’ll stay with the original speedo setup now. So I have an electronic speedo and drive for sale if anyone is interested. I am not sure if it works or not though, so don’t want much, I think the actual speedo might be ok.

I have an electronic speedo and tacho on my 850 and love it.

Jerry
Click to expand...
Jerry,
When you put the small disiccant bag in the speedo,how is that done?My speedometer works great other than the fogging.Any help would be appreciated.
Thanks,
Mike k
 
YING said:
Jerry,
When you put the small disiccant bag in the speedo,how is that done?My speedometer works great other than the fogging.Any help would be appreciated.
Thanks,
Mike k
Click to expand...
Is it an electronic speedo? Might not work with that
 
I'd had my electronic Smith's speedo for two years before I went through heavy rain hour after hour which then leaked like a sieve. Speedo wouldn't work after that. My dealer checked where he bought it and, surprise, surprise, they didn't want to know. Even the cheapest Chinese stuff is at least waterproof these days. And the Smiths are not cheap.
 
Re: Fogging

If you can fit a 5 watt resistor into the instrument, that may be sufficient heat to eliminate fogging.

A typical 5 watt resistor is 7.5 mm dia by 24 mm long. A resistor value of 47 Ohms will pull only 0.3 amps from the electrical system (14,2 ÷ 47 = 0.3)

If you are running down the Interstate with your voltage regulator holding 14.2 volts, the wattage will be 14.2 x 0.3 = 4.26 W, so should be OK.

Slick
 
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