Electronic Tach?

[rude]

Some really nice stuff on here guys, rude, your bike looks great, 75jazz your setup looks great also. I really like Motogadget but it is pricey.
I haven't used it on my XS but have this setup on an old Honda of mine and think it's good. There is a pretty good range of different styles and I found their support pretty good. http://motogadget.com/en/

wow......That would be an early 80's Honda VF750 (4 cylinder V config)..my first "brand new bike".....are they still around? don't see many downunder.
As I recall they had a digital readout for distance and fuel gauge, what you have done looks much much better

 

[pcoumbe]

Yeah an old 82 V45 Sabre, was the first bike I bought here in Philippines, I've seen one more advertised though. Mine got messed up in a flood and ended up looking like this after I refurbished it. There was a lot of broken plastic and the instrument cluster was totalled. Just another unfinished project but it's fun to ride and surprises a lot of newer bikes.
Sorry, I'm hijacking your thread Dot Heton, I'll butt out now.

 

[Paul Sutton]

Old thread but same issues. I have bought a cheap electronic tachometer to fit to a Virago XV1000. I have not got very far with the Virago forum, but hope this issue of mine has been encountered on the XS:

This tacho has a lighting circuit that works when the lights are on and a separate Tachometer circuit with 3 wires: +ve, -ve and signal. The VX has 2 coils and a TCI ignition, but unlike the XS each cylinder has its own pickup coil. We still get one spark from each coil every 360 degree rotation but the cylinders are out of phase with each other due to the V engine.

When the tacho signal line is connected to the -ve side of the number 1 coil I get no rpm readings at all: The -ve side is the one wired to the TCI just like on the XS. Based on TM's old onboard timing strobe setup I wound 11 loops around the ignition lead as a sensor. When connected to the tachometer I get an rpm reading at idle but no change when I rev up. I assume the signal quality is too poor.

So, my questions are:

1. Can anyone suggest why I do not get a suitable signal from the -ve side of the coil and perhaps suggest a suitable modification?
   
2. What would be the minimum circuitry needed to improve the quality of the signal when using a coil wrapped around the ignition lead?

Thank you for any suggestions.

 

[TwoManyXS1Bs]

Paul, I can see 3 forks in this road.

1- The instrument is defective or of a faulty design. No fix there.
2- The instrument becomes damaged, no fix there.
3- The instrument *can* work, if the signal is conditioned for its input.

The signal can be conditioned using combinations of resistors and capacitors, but you gotta know what it's expecting, otherwise shooting in the dark.

Lookup "bandpass filter"...

 

[Paul Sutton]

Thank you TM. I have searched filtering and have obtained a couple of filter circuits which I shall try:


It is worth trying a high value resistor in series where it relies on the tachometers intrinsic capacitance to make a filter. But like you say if I know what the input signal characteristics should be then the job will be a lot easier. If only I had a Scope and Signal generator....

Thank you.

 

[Paul Sutton]

I have tried the 2 filters above but no responce from the tachometer. I wrote a short program for a PIC microprocessor which simulates the 12V signal coming from the ignition coil with the timing set for approximately 4000rpm. When connected to my old electronic tachometer it responds correctly whereas the new "cheap" tachometer from China gives no response at all.

Conclusion: New cheap tachometer is faulty - You often get what you paid for.

 

[TwoManyXS1Bs]

Well, that's too bad.
Good try with your simulator tho'.

Maybe you could attach some long wire clipleads, take it with you, casually connect it to other folks vehicles, see whut happens...

 

[gggGary]

Perhaps reverse the winding direction on the spark wire? if your hot now nearest the coil rewind so the hot is nearest the spark plug?

 

[mrtwowheel]

I'm not understanding this one bit guys!!!!!! Why must the wire coil be used around the spark plug wire? Why can't the tach be wired to the coil and ground like a dwell tach?

Scott

 

[TwoManyXS1Bs]

Scott, the better gizmos have the option of the wrap on the plug wire and/or the coil's (-), and work quite well on either. Others, not so, and may work better on one scheme over the other. One difficulty is the different signal shape with points ignitions vs electronic ignitions...

 

[mrtwowheel]

Scott, the better gizmos have the option of the wrap on the plug wire and/or the coil's (-), and work quite well on either. Others, not so, and may work better on one scheme over the other. One difficulty is the different signal shape with points ignitions vs electronic ignitions...

Thanks, I'll dwell on that.

 

[Paul Sutton]

Time to wrap this up. I ordered another cheap Chinese Ebay 15000rpm tachometer and this too would not work. They have been returned and full refunded received. Possibly a lesson to learn here??

I then spent £43 on a tachometer from a local bike shop. Physically it appears similar to the cheap ones except it was branded YIH TYAN and made in Taiwan. My research indicated that approximately £40 is the going price for the branded product with 8000rpm range (El Cheapos usually cover 12000 or 15000rpm ranges). First thing I did was connect the Tachometer to my simulator and it worked!!!! Guess I got a winner.

Sometimes it is best to buy the branded item via an official supplier at a higher price.