ITI tacho displaying half speed with Sachse ignition

[lazlokovacs]

Anyone know how the ITI electronic tacho works?

I'm sending it a signal from the Sachse ignition brain, but it's reading at half speed.

Weird thing is, even if I flip the switch on the Sachse unit (which is supposed to double or halve the signal) there is no change - the ITI keeps displaying at half speed.

Calvin 2008

[Kiwi Dave]

I experienced this problem when replacing the stuffed speedometer on my California with a replacement.  My California was injected, but the replacement speedometer was meant for a carburettor version.  I think on the latter, the ignition fired on both strokes which is ignored by the motor, but obviously sensitive to the speedo.

Make sense?

[Kiwi_Roy]

The signal you send the tach must be just one cylinder and you need both.
It might be possible to combine the signals with a pair of diodes but I don't have the schematic for the Sachse unit
Can you point to a schematic showing a similar ignition
What have you changed, presumably it worked previously.
Sometimes the counter weigh drops off inside a tacho, shake it and see if it rattles.

[Scout63]

My v50 Sachse EI box has a dip switch for selecting camshaft or crankshaft frequency. Here is a link to the manual:

https://www.gutsibits.co.uk/pr/TheShed/Downloads/SachseSaprisa.pdf

I hope this helps.

[lazlokovacs]

My v50 Sachse EI box has a dip switch for selecting camshaft or crankshaft frequency. Here is a link to the manual:

https://www.gutsibits.co.uk/pr/TheShed/Downloads/SachseSaprisa.pdf

I hope this helps.

Thanks mate,

like I said in my first post, that switch ain't changing anything, thats why I'm here asking....

[guzzista]

Is it possible to wire tach signal directly from coil negative wires? maybe with in-line diodes as KR suggested?.
If the Sachse tach output is only used for that purpose and the bike runs without it it could simply be omitted

[Frenchfrog]

I'd be tempted to send marco an email ...he's normally very quick in answering. info@elektronik-sachse.de

[Kiwi_Roy]

The manual clearly says.
DIP switch No. 2 should be in the up position for crankshaft frequency selection and down position for camshaft frequency selection: You need the Up position.

[lazlokovacs]

kiwiroy -

yes I set the switch in the up position - tacho reads at half speed

then I set the switch in the down position - tacho still reads at half speed

[Kiwi_Roy]

It seem to me when you have the switch in the Down position you would get pulses from 1 OR 10 showing up on wire 7
When you have the switch in the UP position you should get pulses from 1 AND 10
Is there any continuity between the wires 1, 10 & 7 testing with a multimeter, don't be surprised if there's not, it may be capacitive coupled
I could go on guessing until the cows come home
I think you may have to contact the factory, perhaps your unit is faulty.
Did it ever work as advertised?
Is the motor running on both cylinders, both heads getting hot?

 

[Old Jock]

Hi lazlokovacs

As all the other and you know it appears that the tacho was previously reading one pulse per revolution (crankshaft speed) and is now getting one pulse per two revolutions (camshaft speed signal) so its reading 1/2 revs.

Have you flicked the DIP switch  #2 up down a couple of times, I'm wondering if the DIP switch isn't making properly.

If you've got a scope or a DVM that reads frequency I'd check what pulse count you're getting from the Sachse unit with DIP switch #2 in both positions to confirm if that's where the problem is.

I'd also be try DIP switch #1 as well just to see what happens, it's only the rev limiter so it shouldn't be much of a big deal, but that's just me

What is an ITI tacho is that the electronic Veglia unit or something else?

John

[guzzista]

Just curious  as to  the outcome of this post as I am getting ready to install a Sachse ignition on my Cali 1100 (electronic Veglia tach and similar coils )

[lazlokovacs]

in the end, I changed the tach and speedo for new ones from MMB in Germany. Never did figure out the half speed thing, the new tacho is working perfectly... (and yes, if I flick the switch it will read at half speed as well...)

[Old Jock]

Just curious  as to  the outcome of this post as I am getting ready to install a Sachse ignition on my Cali 1100 (electronic Veglia tach and similar coils )

Check the frequency input to the tach with a DMM (multimeter) and then set the dipswitch on the Sachse unit to suit, pretty confident it will be crank speed, but not 100% sure

It looks like lazlokovacs Sachse unit is/was doing what its meant to as stated when he flicks the switch he sees 1/2 speed