For a cheaper digital alternative. This digital tach/ hour meter works pretty good, though it does have a few seconds lag. I have had 2 of these one for over a year until the battery died, then the last one I got it worked fine for 80 scooter hours and 3,000 miles when it started to malfunction.
I'm buying another one. I just use zip ties to mount and it has its own battery and has two wires. One wire you literally wrap around the insulated part of the spark plug wire and the other end you connect to ground or to the frame. Very simple and easy to mount and use.
http://www.ebay.com/itm/Digital-Hour-Me ... 2a2f2c230c
It can be set for 2 stroke or 4 stroke engines. I had one on my 2 stroke motorized bicycle and 150cc scooter last year. You can every engine you own and it keeps track of the hours, rpms, and service time due you set.
I'm going to order another one for my GZ.
I do say that analog tachometer looks sharp on the GZ!