How do I wire up a tach to a vanguard vtwin

I need help wiring up a tach for my mtd. I know that the red wire goes to the positive of the battery and negative to chassis but since I have a vtwin it has 2 magnetos and they're wired together. Do I splice into one of the kill wires or just splice into both to get a reading on the tach?

https://www.atltf.com/t2387-briggs-alternator-specifications-identifier

How I did mine here: Not in depth, but it's real easy and should be the same on the V-twin, use the wire going to the light, pure AC wire.

https://www.youtube.com/watch?v=MnUmeB0ZR3M

i used a sunpro tinytach 2 and i used the 8cyl setting and tapped into the killwire for both coils and it worked for me now for you it depends jsut remeber all these engines max out at 3600rpm so try the 4cyl 6cyl and 8cyl setting and what ever is closer use that setting now mine was dead on 3600rpm

I think I'm gonna get a sunpro tach cause the one I got now is an iequus tach and I can't get the darn thing to work lol I tried hooking it up to both kill wires and it tachs out past 8 grand at idle.

Try hooking it to only one coil kill wire and set it on 4 cyl setting. Vtwins are actually firing the coils 2 times per cycle. Your tach is readin well over twice the rpms of the motor, unless you have removed the governor and are seriously over-revving. Hooking up to only one lead will get ya close

The sunpro mini tach is set up for small engines, and is very adjustable, but you CAN make others work and get them close. DOC Sprocket and I are collaborating on a write up on the subject as we speak.


There are a lot of variables involved

How the tach itself is constructed (I.E. how many pulses is the tach "Looking for" each rev)

is the motor 2 cycle or 4

is the motor 1 or 2 cyl

does the motor's coil ONLY fire on the compression cycle, or does it use the "Lost Spark" method, and fire on the exhaust cycle too.

We'll cover all these things and some solutions in the write up

I have tried splicing into one of the kill wires from the coil and didn't work and I've tried connecting into both and it didn't read at all so I'm stumped

Dipshaw87 wrote:

I have tried splicing into one of the kill wires from the coil and didn't work and I've tried connecting into both and it didn't read at all so I'm stumped

Not the kill wire, but the light source AC wire.

I have a plug that runs out from under the flywheel and it connects to a voltage regulator then a red wire runs from there to the solenoid to recharge the battery where do I hook it up at?

Is that where I need to hook up the signal wire?

I've also heard about wrapping the signal wire around the spark plug wire but I don't think that it would be a very reliable connection

That will give a better connection than you think... the HV pulse will cause a magnetic flux field that induces a current in the conductor lead from the tach. as long as the wire is secured to the plug wire (duct tape works fine) it'll pick up. Remember, it's probably firing once per rev

So I should wrap the signal wire around the plug wire a bunch of times then tape it and it'll work?

And does it matter which plug I tape it to?