If you have a tack, just observe the rpm where you get the highest reading on the scale. You don't want to hold the throttle down for any length of time, it should just take two or three seconds to get a reading. People laugh at this, but, other than track testing, there's no better way to set the clutch. And you can do this at home when you have time, rather than at the track where things can get a little rushed.Yes have a tack.....( not the best at being able to look thru it ) but I am reading up on that, so I can help my son with this. Thanks for the info.