Rpm question

[butler]

I have my Gast 2565 on a 6.5 hp motor. I have a laser rpm unit.. I need pump to be running at 1725 rpm... Do I measure it while it's hooked up to the Releaser or ?? Not quite sue how to set rpm's

[madmapler]

You should probably check it under a load. Gas engines fluctuate more. Really though, as long as you keep oil in it, I basically go by the sound of things once you're used to it. I actually overspeed them a little(1800 +-) when things are flowing strong. Pay attention to the heat and don't enclose them if you can.

[butler]

I have the pump on idle and rpm's are reading...1900... Seems high?? I have a 4" wheel on pump and a 2" on motor maybe I need a bigger wheel on pump? I am taking rpm reading off motor shaft... Is that correct?