Smiths Electronic Tacho Error

Status
Not open for further replies.
robs ss

robs ss

VIP MEMBER
Joined
Aug 16, 2016
Messages
3,551
Country flag
Recently my Smiths electronic tacho has started reading about 12% too high. (60mph is now 3900rpm instead of just under 3500).
The error appears to be consistent across the rev range.
Anyone know if this is fixable - and if so how to recalibrate?
Thanks in advance.
Cheers
 
If X rpm at Y MPH is your measure… how do you know it’s the rev counter and not the speedo ?

AFAIK rev counters cannot be calibrated. They simply count ‘signals’ from your ign system.

Unless it’s it possible it’s getting ‘noise’ from somewhere ?
 
Fast Eddie said:
If X rpm at Y MPH is your measure… how do you know it’s the rev counter and not the speedo ?

AFAIK rev counters cannot be calibrated. They simply count ‘signals’ from your ign system.

Unless it’s it possible it’s getting ‘noise’ from somewhere ?
Click to expand...
I double checked the speedo with GPS, and my speed at 60mph is consistent with other traffic.
I have today been in contact with Howard Instruments (Australian Agent) and he has forwarded the issue to Caerbon/Smiths.
We'll see!
Cheers
 
robs ss said:
I double checked the speedo with GPS, and my speed at 60mph is consistent with other traffic.
I have today been in contact with Howard Instruments (Australian Agent) and he has forwarded the issue to Caerbon/Smiths.
We'll see!
Cheers
Click to expand...
Rob,
I had an issue with my speedo a couple of years back and got in touch directly with CGI and they were very helpful in getting my problem resolved.Since then no problems with either the speedo or tach. I love the way they work with no bouncing needles.
Mike
 
YING said:
Rob,
I had an issue with my speedo a couple of years back and got in touch directly with CGI and they were very helpful in getting my problem resolved.Since then no problems with either the speedo or tach. I love the way they work with no bouncing needles.
Mike
Click to expand...
Sorry for my ignorance - who are CGI?
 
Carbourn(sp.)Gauge Instruments
They are the ones building the gauges with the Smiths name. I will see if I still have the address but I think your local rep is your best bet. I am not sure with the spelling but will see when I get home.
Mike
 
YING said:
Carbourn(sp.)Gauge Instruments
They are the ones building the gauges with the Smiths name. I will see if I still have the address but I think your local rep is your best bet. I am not sure with the spelling but will see when I get home.
Mike
Click to expand...
Thanks Mike - found them - they are CAI Gauge, but as you say, I'll see how the chain with the rep goes first.
www.caigauge.com

Motorcycle Instruments from Caerbont Automotive Instruments

Standard and customised motorcycle instruments for OE manufacturers end users and Smiths enthusiasts
www.caigauge.com www.caigauge.com
Cheers
Rob
 
Can you use another tachometer to confirm your observation? Many timing guns with an Advance function will also display rpm. Also some multimeters and sound meters have tacho functions.
 
If it is the same as the one I just installed... You put the light blue wire to negative side of battery with switch off for 10 seconds. Turn switch on and hand will sweep face and settle to the 0 or 1000 mark. Then quickly disconnect and reconnect blue wire. Hand will sweep and settle on the 2000 rpm position. It is now reset for a twin cylinder with wasted spark. Same for neg or positive ground. Try to download instruction page from manufacturer to be sure. Poorly worded instructions though. Also, I was disappointed in the tiny wire gauge size and the fact the lead was 2" to short and had to add length to every wire used. Real cheap....thinking they feel like off-shore crap.
 
I had exactly the same problem, the gauge was working fine and then started reading high, it turned out to be a loose connection to the gauge . I can't remember which wire though, I just gave each one a bit of a tug, and one came apart. recrimped it and all was well again.
 
TheCounty said:
If it is the same as the one I just installed... You put the light blue wire to negative side of battery with switch off for 10 seconds. Turn switch on and hand will sweep face and settle to the 0 or 1000 mark. Then quickly disconnect and reconnect blue wire. Hand will sweep and settle on the 2000 rpm position. It is now reset for a twin cylinder with wasted spark. Same for neg or positive ground. Try to download instruction page from manufacturer to be sure. Poorly worded instructions though. Also, I was disappointed in the tiny wire gauge size and the fact the lead was 2" to short and had to add length to every wire used. Real cheap....thinking they feel like off-shore crap.
Click to expand...
County,
I had all the same problems with the length of the wires. I thought that it was just me as I had to lengthen all but the ones for the speedo sensor.Everything has worked well since and like the way they work
Mike
 
Tornado said:
Can you use another tachometer to confirm your observation? Many timing guns with an Advance function will also display rpm. Also some multimeters and sound meters have tacho functions.
Click to expand...
Yes - I have external strobe gun - just not the knowledge on how to fine adjust these newer ones.
 
TheCounty said:
If it is the same as the one I just installed... You put the light blue wire to negative side of battery with switch off for 10 seconds. Turn switch on and hand will sweep face and settle to the 0 or 1000 mark. Then quickly disconnect and reconnect blue wire. Hand will sweep and settle on the 2000 rpm position. It is now reset for a twin cylinder with wasted spark. Same for neg or positive ground. Try to download instruction page from manufacturer to be sure. Poorly worded instructions though. Also, I was disappointed in the tiny wire gauge size and the fact the lead was 2" to short and had to add length to every wire used. Real cheap....thinking they feel like off-shore crap.
Click to expand...
Yes - than grounding of the blue wire is to set it up for the correct cylinders/coils selection. I have those instructions (see below). That's not my problem though - it was set up and operating fine - then suddenly started reading high.

Screen Shot 2022-07-25 at 2.06.26 pm.png
 
Strange days indeed! Most peculiar momma...

Have not altered anything but on today's ride the tacho is reading correctly again.
Haven't heard back from CAI Smiths yet - but an intermittent error doesn't sound good.
We'll see...
 
robs ss said:
Strange days indeed! Most peculiar momma...

Have not altered anything but on today's ride the tacho is reading correctly again.
Haven't heard back from CAI Smiths yet - but an intermittent error doesn't sound good.
We'll see...
Click to expand...
Rob,
Try to get to Peter Wilkerson at CAI.He is the man in charge and who helped me with my problem.
I hope it stays good for you !
Mike
 
Well, the performance of my smiths electronic tach has been reasonably constant, with only a couple of glaring errors (short lived).
But it got me thinking, how accurate has this thing ever been?
So I wired up one of those Yamaha inductive tacho/hour meters (just needs some wraps of the wire around one of the HT leads)
It reads double the rpm because of the wasted spark - really should get a 2-stroke one but this works for me - just got to halve the indicated rpm.
After about 100 miles what I have found is the Yamaha unit is reading about 130rpm below the Smiths across the rev range.
Is the Yamaha right?
Has the Smiths always been wrong?
Next step is to manually calculate what the rpm should be at a given speed (GPS verified)
Got to count "teeth" on the cNw belt drive.
Work out ratio for 21t countershaft sprocket, and
Measure the circumference of the rear tyre.

I'll post results when done.

BTW, has anyone else done this or do you all (those with Smiths e/tachos) blindly believe what is says is true?

Cheers
Rob
 
A non-contact optical tachometer is just the thing for such measurement; I used them extensively when I was doing a lot of marine work. Attach a piece of reflective tape to the rotating part you want to measure, turn on the component, point the reader at the component and it the reader counts the number of times the tape passes. They work great.

When I bought mine years ago they were nearly 200 bucks, now I see them for less than 20! Looks like a decent one is under $30:

Amazon product ASIN B09TK8WVF6
 
Anyone know what the number of teeth on the front and rear pulleys of the cNw belt drive is?
Requires a fair bit of disassembly to count!
Cheers

Edit: Just looked on Matt's site (should have done that first) 32 front 70 rear
 
Status
Not open for further replies.

Similar threads

Jerry Doe
Smiths electronic speedo transducer
2
Replies
22
Views
1,004
YING
YING
S
  • Locked
Smiths electronic tacho failure
Replies
6
Views
890
Fullauto
F
Derek Wilson
  • Locked
Who Does Smiths Electronic Instrument Repairs?
Replies
16
Views
1,072
Stephen Hill
S
MS850
  • Locked
Smiths Electronic Gauge Instructions
Replies
4
Views
1,414
YING
YING
Jerry Doe
  • Locked
Smiths electronic tacho and pazon
Replies
5
Views
960
Jerry Doe
Jerry Doe
Back
Top