How to connect a GSX R 1100 Tacho on a GS 1000 S

[John Kat]

I'm currently rebuilding a GS 1000 "special " with full GSX R 1100 K suspension and brakes. The bike will also use the speedo and tacho from the GSX R.
The issue is to get an electrical signal to the tacho . The CDI on the GS 1000 doesn't provide an output signal for this purpose.
I'm sure one can get it working by taking the signal from the coils somehow.
Has anyone done it before?

 

[posplayr]

I had always assumed it was the negative coil wire, but looking at the schematic i see the tach is driven by the GSXR ignitor (ps there is no CDI).


Anybody done this?

I tried to test a GSXR 1st gen tach using my coil signal and it did not work. Not sure now if that is should have worked at all.

 

[Guest]

Been looking to do this to my Gs1000s, know it can be done because i have seen it done.
come on someone must know how its done?.
or is it a secret.

 

[John Kat]

I would definitely not connect the primary winding of the coil directly to the tacho input as the voltage could raise up to 400 volts !
The trick is most probably to connect the coil through a large resistor ( 1M ohms?) to the tacho but by limiting the voltage at the input by a zener diode in parallel in order to clamp the maximum voltage at 5 or 12 volts?
If someone can connect a scope to a GSX R tacho and give us the maximum voltage recorded it would help a lot.

 

[Guest]

Don't know if they are the same but I used a set of gages from a 97 bandit on my gs1100 and I just tied into the neg side of the coil and it works fine.

 

[posplayr]

Don't know if they are the same but I used a set of gages from a 97 bandit on my gs1100 and I just tied into the neg side of the coil and it works fine.

That would be the simple answer but the GSXR has a separate wire from igniter to the tach suggesting that the negative side coil wire is not what is used.

A voltage divider with voltage limiting diode would make sense, but it would be nice to confirm if someone had already been through this. I recently did something similar to get am RPM input into an Innovate LMA-3 device.

 

[John Kat]

After a lot of hesitation I finally connected the GSX R 1100 tacho input directly to the negative side of one of the ignition coils....and IT WORKS!
Not ideal to set the iddle as the first graduation starts around 3000 RPM but it's great to see the needle move up to the 9000 mark

This was the ( almost) final touch to my own "Wes Cooley/Yoshimura GS 1000 Special".
I could publish my notes on this subject as a complement to the wonderfull job done by 80GS1000.
Let me know if anyone is interested?

 

[posplayr]

After a lot of hesitation I finally connected the GSX R 1100 tacho input directly to the negative side of one of the ignition coils....and IT WORKS!
Not ideal to set the iddle as the first graduation starts around 3000 RPM but it's great to see the needle move up to the 9000 mark

This was the ( almost) final touch to my own "Wes Cooley/Yoshimura GS 1000 Special".
I could publish my notes on this subject as a complement to the wonderfull job done by 80GS1000.
Let me know if anyone is interested?

Glad it works