I installed a $35.00 tach 2 years ago that picks up the signal from the spark plug. You just ground the thing and wrap the hot wire around the plug wire. It's all right, but... I am sure I saw someone on this web site with a real tach. The chrome job with a dial face. I saw some online, but the guy wrote back that the spark plug wire installation will not work, that the tach needs a signal. ?? Anyone have instructions? I didn't find anything in the tech section.  

tach's are easy to put on.    Orange wire under the tank is switched power (for the tach and for the light blub).  The black wire (with a stripe) on the coil is the lead to run the tach.   You just need to find a nice spot to use as a ground.  I used the coil mount screw.

I have a thread in the tech/ref section which lists tach's that are known to work on LS650's.     I think it's now about 3 or 4 pages back.    ..... Now that no one is policing the Tech Ref section to move the questions people keep asking there (sorry the old Sarg in me made me say that)

I loved my tach.  Analog tach (tach with a moving needle) is the way to go.   I had it mounted up on the bars between the risers.   After a while I was using it as a speedo.   A certain RPM is a certain speed.  

JOG if your in 4 gear your doing 4/5 of the speed of high gear and so on.