[Hotfingrs]

First you want to vary the rpm during this 20 min break in....nothing lower than 2000 and you really don't need more than 3000. Best way is to set the idle screw on your carb until you get the desired rpm, then every couple of mins just pull on the throttle linkage to change the rpm for a little bit. as far as listening for anyting...just whatever you would listen for during normal operation..