I have seen the video on the Savage website that lets you hear the sound of the Savage at idle so that you can estimate your bike's RPM at idle speed.  However, I would like to use a tachometer to measure my idle speed.

My questions are:  
  - Have any of you used a tachometer to actually measure your bike's RPM at idle speed?  If so, where/how do you hook up the tachometer on the bike?  
 - Do you have a suggestion on where to buy a tachometer? (I don't want a bike mounted tach, just a tachometer instrument to hook up and test the idle RPM when needed).

As a side:
I have an old tachometer/dwell meter that according to the instructions says to hook up one clip of the tach/dwell meter to the negative coil post of the vehicle (LS650) and the other clip of the instrument to ground.  However, this instrument is so old that it was used in the days of the points and condenser era ... and I don't know how accurate the instructions are for today's modern vehicles.  However, if the instructions are still correct, I don't know where the negative coil post is on the LS650?  Does anyone know where the negative coil post is?

Thanks for any help you can provide,
Ron G

What Dave said ↑

These definitely work well and you can use them on your lawnmower, generator, or whatever.  Good to have around.  Wrap the wire around the spark plug wire five times and zip tie...done.