Test tach/over rev.

Is there a inexpensive test tach for the 4 stroke F115 motors, I just want to check the performance of my prop/motor. Does the F115 have a governer on it so it will not blow up if run wide open and over rev? I have not run the motor wide open yet and I was worried about doing it with out a tach to watch.

[boats.net]

The rev limiter on a F115 is at 6200 rpm's. You can get volt/ohm test meters with a rpm adapter to read rpm's but the Yamaha Tach may be cheaper.