Racing

I have a VDO tach on a yamaha 600 twin that acts strange. I just got it back from testing/calibration and installed it. It seems OK at idle (1,500) but is incrementally off as the RPMs go up, sometimes showing 10,000 rpm on the track stand (i haven't had it out yet) . I have the tach grounded to the motor, 12+ from the battery to the tach, and 12- from the barttery to the motor and the tach. This is my first time hooking this up...any suggestions? Seems like a ground feedback problem to me but not sure!

 The tach needs to be set for your engine. There are dip switches inside that need to be reset for your application.

the switches were set when it went out for cal for a 2 stroke twin thanks for the reply though!

You sent it out for calibration in which all dipswitches get shut off, so when you got it back what switches were on??

You should have with a stock Ignition 6 pole  Switches 1,2,3,on and 4 off. Remember on is towards the numbers  and off is away from numbers.

Wiring: green to tach signal.

Black to battery -

Red to Toggle Switch and than on down to battery +

Ground from battery to good engine ground.

If  you want Illumination in gauge to work, connect red and white together before toggle.

Also these tach like voltage meaning have a good battery fully charged. Just remember just because its 12 volts is it really enough to run the tach???

Yeah the switches were not right, Got it now I think, Thanks for the reply!

Another common mistake people make is not to run lights or grip heaters.  You need to do the grip heaters in order to load the stator.  Most stators have 3 coils for ignition and the rest is for lights, heaters, etc.

OK here is how I finally got the Tach to work. It is a older yamaha twin two stroke. i had to set the dip switches to an 8 cylinder  to get it at the correct engagement and idle RPM. Then at max RPM it was flaking out so I put a 10k ohm resistor inline to load the stator since there were no handwarmers/lights. Thanks to Doc and Nick for the help, thought this post may help others